Questions related to the final exam may be directed here and will be answered up to 24 hours before the exam.
Final Exam Friday Dec 10 9-12 AM in the GYM (All Chem 101 student will write together)
The final exam is cumulative and will cover the entire course with a weighting towards material not covered on the midterms. You must pass both the lecture and lab to pass the course.
Old copies of exams are available at ZAP in the student union.
Solved exams are being sold in Elliot (3rd floor) until Dec 2.
Pre-Exam Review Tutorials
There will be three review sessions. They are open to all Chem 101 students.
Tuesday December 7th 10:00am-noon Sci B150 (Bob Wright Centre) (run by Dr. Sirk)
Also NEW Booking! Tues Dec. 7 from 1 - 3 pm MAC A144- Chem 101 review session (Dr Sirk)
-both review sessions will be identical-
Wednesday December 8th 10:00-11:30am SSM A120 (Social Sciences & Math) (run by Dr. Briggs)
Thursday December 9th 10:00-11:30am Sci B150 (Bob Wright Centre) (run by Dr. Codding)
Do we need to know the common names for carboxylic acids? eg. do we have to call it benzoic acid, or would it be accepted to call it phenyl methanoic acid?
ReplyDeleteThanks.
For #11.77 (b), how do you know SiO2 is a covalent network solid?
ReplyDeleteSiO2 structure: The structure of SiO2 is within the text (pg459). SiO2 is sand/glass/quartz.
ReplyDeleteNaming requirements: Naming of relatively SIMPLE alkanes, alkenes and alkynes including cis
ReplyDeleteand trans alkenes and the simple cyclic alkanes (rings 3, 4, 5, and 6) and simple alkyl halides; no cyclic alkenes. You do not need to name alcohols, aldehydes, ketones, aromatic compounds, esters, amides, etc. However, you will need to be able to recognize them when given a drawn example. You need to understand isomers (structural/constitutional).
So... from your email, reading for organic chem IS 25.7, not 25.5?
ReplyDeleteNope, it's 25.5. I'll send out the errata.
ReplyDeleteI'm just wondering, for the molecule in 25.7, CH3CCCH2COOH, would that be named as an alkyne with a carboxylic acid substituent or as a carboxylic acid with an alkyne functional group?
ReplyDelete(If this is a sort of molecule we should be able to name, could you please explain how to do it?)
Thanks!
Does it matter if you put a hyphen or a comma between the subtituent names? e.g. are both 'cis-6-methyl, 3-octene' and 'cis-6-methyl-3-octene' correct? thanks.
ReplyDeleteFor #25.32b) the addition of H2O to trans-2-pentene using H2SO4 as a catalyst, does it actually make two products or does it mean there are two possible products?
ReplyDeleteRe CH3CCCH2COOH, As per the post above (Nov 27 9:30) you don't need to name items with functional groups.
ReplyDelete(The name is pent-3-ynoic acid acid)
'cis-6-methyl-3-octene' is correct
ReplyDeleteThere are two possible products, but this falls under the mechanism of the reaction so you don't need to predict them.
ReplyDeleteProblem 2 - Naming Organic Molecules I in the tutorials named the first molecule as 5-ethyl-3,4-dimethyloctane; however, if you numbered from the opposite direction it would be 4-ethyl-5,6-dimethyloctane, the leading number would be lowest..
ReplyDeleteAre we trying to make the smallest total numbers, or the smallest leading number?
Thanks
I'm fairly sure that you want the number of the first substituent you encounter to be the lowest, so 5-ethyl-3,4-dimethyloctane would be right.
ReplyDeleteWill an answer key be posted for the practice final exams at the back of the Chem 101 Lab Manual?
ReplyDeleteThanks!!
Does polarizability only refer to induced dipoles, or dipoles of any kind? Would a polar molecule (e.g. HF) be hard to induce a dipole in?
ReplyDeleteDo we need to know the common names of acids? For example, benzoic acid, acetic acid, etc.?
ReplyDeleteI have an exam from 9:00 - 12:00 on the Tuesday you are giving you review... I reallyy wanted to attend you session. Is it possible for you to bump the time tomarter 12:00? I am sure many other students will be writing physics exams at this time who would love to attend your session as well :)
ReplyDeletePlease and thank you!
I am having a lot of trouble figuring out how to determine melting and boiling points. Is there a pattern or method that I just missed in class?
ReplyDeleteFirst off: Apologies on my late replies. I turned off the requirement that required me to review the comments before they publish that I was using to filter spam. I didn't realise that also turned off the notification that I recieved comments as well.
ReplyDeleteProblem 2 - Naming Organic Molecules I in the tutorials named the first molecule as 5-ethyl-3,4-dimethyloctane; however, if you numbered from the opposite direction it would be 4-ethyl-5,6-dimethyloctane, the leading number would be lowest..
ReplyDeleteAre we trying to make the smallest total numbers, or the smallest leading number?
Answer: Neither, we are trying to make the smallest number possible for one of the substituents. 3 is less than 4, so we pick the numbering that gives 3.
What will we need to know about functional groups? Do we need to know the formation of all different functional groups? Or just the ones we covered in class such as carboxylic acids, esters, and amides?
ReplyDeleteAnswer keys for the final exams are available (were available) from the Chem Society only.
ReplyDeleteRe:Does polarizability only refer to induced dipoles, or dipoles of any kind? Would a polar molecule (e.g. HF) be hard to induce a dipole in?
ReplyDeleteAnswer: Good question that requires a somewhat subtle answer. Polarizability does only refer to induced dipoles, but molecules with permanent dipoles can have a polarizability on top of their dipole. HF would be difficult to induce a dipole in, but that would arise more from the small size than the electronegativity difference.
The review sessions took some room juggling to start with so they can't be moved.
ReplyDeleteTwo things:
1)There are two other review sessions and you may find those even more useful as the other instructors will have a slightly different viewpoint and maybe some different explanations that make sense.
2)I will post the notes for review session online.
Functional groups: Just the ones covered in class (and in this case the downloadable lecture notes cover just about everything I covered in class)
ReplyDeleteWhere are/will the calculated marks posted for us to check? Thanks.
ReplyDeleteDo we have to memorize the specific properties of diamond and graphite?
ReplyDeleteWill the slides for the last few sections be posted on your website?
ReplyDeleteIs it okay to name the structural isomer neopentane (c5h12) as 2,2-dimethylpropane?
ReplyDeleteDo we need to know that methane is natural gas and other facts like that?
What do we need to know about Alcohols, Ketones and Aldehydes? It talks about it in the book but we only have notes on carboxylic acid, esters, amines and amides.
ReplyDeleteIs benzene considered a cycloalkane?
ReplyDeleteThe book says to name alkenes by numbering closest to the double bond, buy what if I have a halogen at the very end of one side but that side will make the double bond not the lowest number? What do I pick for the numbering?
ReplyDeleteAm I supposed to be able to name multiple triple or double bonded alkynes and Alkenes? And how do I name a multiple triple bonded alkyne?
ReplyDeleteDo we need to understand the mechanism of addition reactions?
ReplyDeleteThanks!!
Do we need to know the Friedel-Crafts Reaction?
ReplyDeletedo we need to memorize the formation of PET and nylon?
ReplyDeleteDo we have to memorize how the different functional groups form? (oxidation etc.)
ReplyDeleteIs there an acid equilivant for sopanification? And do we need to know sopanification?
ReplyDeleteDo we have to be able to name the molecules with the functional like amide or ester?
ReplyDeleteFor edition 10, what sections do I have to read for chapter 12?
ReplyDeleteCalculated marks are posted outside Elliot 246. They will not be posted on a web page due to confidentiality issues.
ReplyDeleteDiamond and graphite: Yes you should know the bonding within the molecules (Both are covalent network solids-Diamond has sp3 C and only covalent bonds, so strong and brittle. Graphite has covalent bonds (aromatic) along the flat benzene layers that conduct electricity. Between the layers are VanderWaal forces. These are weak and the layers can slide over one another)
ReplyDeleteOverhead slides are currently posted here:
ReplyDeletehttp://web.uvic.ca/~asirk/overview.htm
and will be cross posted
http://web.uvic.ca/~asirk/
Re: Is it okay to name the structural isomer neopentane (c5h12) as 2,2-dimethylpropane?
ReplyDeleteYes, that is the correct IUPAC name
Do we need to know that methane is natural gas and other facts like that?
Yes for common material (methane=gas, gasoline=liquid, gasoline is around C8, hence the term high octane). More importantly, you should know how boiling points increase with increasing molecular weight.
Re:What do we need to know about Alcohols, Ketones and Aldehydes? It talks about it in the book but we only have notes on carboxylic acid, esters, amines and amides.
ReplyDeleteYou should know
-how to draw them
-the hybridisation of the carbon (and oxygen) in each
-how to recognize them
-that they are polar
-that an alcohol can be oxidised to an aldehyde
-that an aldehyde can be oxidised to a ketone
-that alcohol can react with carboxylic acids to form esters
-that esters can be hydrolysed to form alcohols and carboxylic acids.
Re:Is benzene considered a cycloalkane?
ReplyDeleteAnswer: Nope, benzene is aromatic. A cycloalkane can only have single bonds (all C must be sp3 hybridised)
Re: The book says to name alkenes by numbering closest to the double bond, buy what if I have a halogen at the very end of one side but that side will make the double bond not the lowest number? What do I pick for the numbering?
ReplyDeleteAnswer: The double bond numbering trumps the halogen (or any other substituents).
Re: Am I supposed to be able to name multiple triple or double bonded alkynes and Alkenes? And how do I name a multiple triple bonded alkyne?
ReplyDeleteAnswer: Nope, you only get one double or triple bond for naming purposes.
Re: Do we need to understand the mechanism of addition reactions?
ReplyDeleteThanks!!
Answer: No You’re welcome!
Re: Do we need to know the Friedel-Crafts Reaction?
Answer: Not this year, but feel free to memorise it for future reference in second year.
Re:do we need to memorize the formation of PET and nylon?
Answer: Given the structure of PET or nylon or a similar polymer, you must be able to give the starting materials and products (ie PET and water). This will be limited to the formation of an ester linkage or an amide linkage.
Re: Do we have to memorize how the different functional groups form? (oxidation etc.)
Re: Yes, every reaction given in class is testable. These were also covered/listed in the downloadable lecture notes.
Also, next year, I will use tumblr to host my blog because it would allow me to comment directly under your comments. I almost switch mid-stream this year, but decided we had enough webpages already.
ReplyDeleteFor edition 10, what sections do I have to read for chapter 12?
ReplyDeleteThe sections labelled Polymers and Semiconductors.
For everone: The course content is revised to the following:
MODERN MATERIALS. (Chapter 12.1-12.3, 12.6) Polymers, semiconductors
This means liquid crystals and superconductors are NOT testable.
Re: Is there an acid equilivant for sopanification? And do we need to know sopanification?
ReplyDeleteAnswer:Sopanification (which means soap making because that’s how soap is made and organic chemists tend to use some ancient words) is the reaction of an ester to a carboxylic acid and alcohol.
The same reaction can be done in acid and is called hydrolysis.
Also, the reaction is in equilibrium and by driving off the water or adding more water, one can force the reaction in either direction.
Re: Do we have to be able to name the molecules with the functional like amide or ester?
Answer: Reposted from above, but important enough to say twice: Naming requirements: Naming of relatively SIMPLE alkanes, alkenes and alkynes including cis and trans alkenes and the simple cyclic alkanes (rings 3, 4, 5, and 6) and simple alkyl halides; no cyclic alkenes. You do not need to name alcohols, aldehydes, ketones, aromatic compounds, esters, amides, etc. However, you will need to be able to recognize them when given a drawn example. You need to understand isomers (structural/constitutional).
Do we need to know band theory for the transition metals, i.e. with pi anti-bonding orbitals? Or just the sigma bonding and anti-bonding orbitals?
ReplyDeleteThanks
For band theory you just need to know that it can explain properties of metals (hardness, melting point etc..) but not how it explains those features.
ReplyDeleteDo we need to know about "the silicon chip", "solar energy conversion" and "semiconductor light-emitting diodes" from chapter 12?
ReplyDeleteI don't remember covering these in class
which pages for 12.3 do we need to know?
ReplyDeleteWhat is PET?
ReplyDeleteQuestion 23.23c in the textbook has the answer: para-dibromobenzene
ReplyDeleteIs that something we should know how to name?
what does the para mean?
Question 25.45 from the textbook asks you to draw the condenses reactions between a) benzoic acid and ethanol b) ethanoic acid and methylamine c) acetic acid and phenol
ReplyDeleteare we supposed to know what these look like?
Was the section on Proteins in chapter 25 included? i.e. do we need to know how to do question 25.55 "what is an a-amino acid? how do amino acids react to form proteins? Draw the bond that links amino acids together in a protein. What is it called?"
ReplyDeleteDo we need to draw substitution reactions like on page 1069 of the 11th edition? Would a question like the "give it some thought" on that page be asked?
ReplyDeleteHello,
ReplyDeleteDo we need to know anything on ceramics?
Thanks!!
Is doping something we need to know? Also, exactly what sections are we supposed to read in chapter 12, ed10? It is very confusing!! Sorry!!
ReplyDeleteRe: which pages for 12.3 do we need to know?
ReplyDeleteAnswer: 12.1 (all) 12.2 (all) 12.3 484-485,488, 489,492, 12.6:499-505 (all)
Re: What is PET?
Answer: It is the condensation polymer: polyethylene terephthalate. You wouldn’t be asked to give the full name or draw the structure of PET outright. However, if given the structure of PET you should be able to give the two molecules that make it up or if given the parent monomers, you should be able to draw the resulting polymer of the condensation reaction.
Re: Question 23.23c in the textbook has the answer: para-dibromobenzene
Is that something we should know how to name?
what does the para mean?
Answer: Nope, (para means the two substituents are on direct opposite sides of the ring 1,4 position)
Re: Question 25.45 from the textbook asks you to draw the condenses reactions between a) benzoic acid and ethanol b) ethanoic acid and methylamine c) acetic acid and phenol
are we supposed to know what these look like?
Answer: You can find the structures in the text (or google image search). While you wouldn’t be asked in words for the product of those reactions in exactly that fashion, if the structures were given to you (drawn out), you should know the reactions.
Re: Was the section on Proteins in chapter 25 included? i.e. do we need to know how to do question 25.55 "what is an a-amino acid? how do amino acids react to form proteins? Draw the bond that links amino acids together in a protein. What is it called?"
Answer: You don’t need to know amino acids separately, but by looking at an amino acid and a protein, you should be able to answer the last 3 of the 4 questions by using what is known about general polymer chemistry.
Re: Do we need to draw substitution reactions like on page 1069 of the 11th edition? Would a question like the "give it some thought" on that page be asked?
25.10 yes, 25.11 no, 25.12 yes, 25.13 no (but you will see that in second year organic and inorganic as well)
The give it some thought question is quite a good one. If you have difficulty with it, draw all the hydrogens on the naphthalene structure.
RE:Do we need to know anything on ceramics?
Ceramics, Liquid Crystals and Superconductors will not be covered on this final.
Re: Is doping something we need to know? Also, exactly what sections are we supposed to read in chapter 12, ed10? It is very confusing!! Sorry!
ReplyDeleteYes, doping of semiconductors is something that must be known. Read the sections on semiconductors and polymers. (The doping may be in the metallic bonding section. It is in the 9th edition). The section titles are the same in the 11th and 10th edition, but the orders are different.
Hi Dr. Sirk,
ReplyDeleteI am kind of confused about what exactly will be on the final exam, as some of the reading material has changed. Is it possible to re-post the exact reading material that will be covered, or at least which sections have been changed? Thank you in advance.
The final exam covers the entire course.
ReplyDeleteOnly the readings for Chapter 25 and Chapter 12 have been changed (Shortened in both cases)
Chapter 25 is 25.1-25.5
-do not need to know mechanism
Chapter 12 is 12.1-12.3 and 12.6
With focus on the following pages:
12.1 (all) 12.2 (all) 12.3 484-485,488, 489,492, 12.6(all)
All readings are posted
http://web.uvic.ca/~asirk/overview.htm
Would we need to know how to do the reactions of esters like sample exercise 25.6 on page 1077?
ReplyDeleteDo we need to memorize all the substituents?
ReplyDeleteRe: reactions of esters
ReplyDeleteAnswer: Yes, you need to know the hydrolysis reaction and how to predict the products of the hydrolysis of esters. (You should also be able to do the condensation reaction to produce esters)
For the substituents, you must know methyl through decyl, all the halides, hydroxide and nitro.
ReplyDeleteFor each of the following semiconductors, which one will have the larger band gap and why:
ReplyDeletea)CdS or CdTe
b)GaN or InP
c)GaAs and InAs
Thanks!
how can CH3NH2 and CH3OH hydrogen bond with their same molecules? (i.e. CH3NH2 and CH3NH2)?
ReplyDeleteThe stronger the bond, the greater the bandgap. While compound semiconductors were not focused on, this is a good question to consider the bond strength. (Treat these as ionic bonds, so consider charge first, size second)
ReplyDeleteHydrogen bonding can only with more than one molecule. It occurs between the H (which is covalently bonded to O, N or F and therefore has a high partial positive charge) and the O, N or F on the the other molecule (Which has a high partial negative charge)
ReplyDeleteFor the questions:
ReplyDeletehow can CH3NH2 and CH3OH hydrogen bond with their same molecules? (i.e. CH3NH2 and CH3NH2)?
isn't there only hydrogen on the outside of both of these molecules?
Why can CH3F not hydrogen bond?
ReplyDeleteA solid has a very high melting point, great hardness, and poor electrical conduction. This is a(n)
ReplyDelete__________ solid.
a. covalent network
why is it not an ionic solid?
Are we expected to draw a molecular orbital diagram like assignment question 12.9 asks?
ReplyDeletehow are cyclic alkanes structural isomers of alkenes?
ReplyDeleteHello,
ReplyDeleteDo covalent networks only for when there are an average of 4 electrons on each atom (4A atom element semiconductors or compound semiconductors like GaAs)?
Re: how can CH3NH2 and CH3OH hydrogen bond with their same molecules? (i.e. CH3NH2 and CH3NH2)? isn't there only hydrogen on the outside of both of these molecules?
ReplyDeleteThe Oxygen and Nitrogen are also exposed. We didn’t get into the details in lecture, but the hydrogen bonding is actually between the hydrogen and the lone pair or pairs on the N,O,F. So the lone pairs on oxygen and nitrogen (and fluorine) are quite available. If you draw out the structures in a 3-D fashion taking into account the lone pairs this should be more apparent.
Re: Why can CH3F not hydrogen bond?
There is no covalent bond between a H and the F, as the F is bonded to the C.
Re: A solid has a very high melting point, great hardness, and poor electrical conduction. This is a(n)
__________ solid.
a. covalent network
why is it not an ionic solid?
Can you please give me the reference for the question?-Thanks
Re: Are we expected to draw a molecular orbital diagram like assignment question 12.9 asks?
There will be questions in the assignments that encourage a deeper level of thinking about the questions and the concepts involved than would be explicitly testable. So if you can understand the concepts at a deeper level, it helps with the overall comprehension. If you look over the old finals you get a good idea about what questions would be asked. In summary, it is unlikely that you would be asked to draw that, but understanding why it looks the way it does may help you answer other questions.
Re: how are cyclic alkanes structural isomers of alkenes?
They have the same chemical formula and different connectivity. For example cyclopropane is C4H8. Trans-2-propene is also C4H8.
Is there a difference between plastics and thermoplastics?
ReplyDeleteThanks
Covalent networks exist anytime there is infinite covalent bonding through the molecules. Graphite is a covalent network and is sp2 hybridised C.
ReplyDeleteQuestion 4 from quiz 8
ReplyDeleteA solid has a very high melting point, great hardness, and poor electrical conduction. This is a(n)
__________ solid.
a. covalent network
b. ionic
c. metallic
d. molecular
e. metallic and covalent network
Earlier you said we don't need to know the Silicon Chip or Semiconductor LED sections, but then you said pages 489 and 492 (which are on these two topics) are included. Do we need to know it? This is all very confusing.
ReplyDeleteThanks in advance.
Hi Dr. Sirk,
ReplyDeleteIn regards to the second midterm, written question #4 c, how would you discard the less stable resonance structure - or better said, how do you know that it would be less stable?
Thank you!
10. If one compares compound A composed of nonpolar molecules with compound B composed of polar molecules, and both molecules have the same molecular formula then it is true that:
ReplyDeleteA. both compounds have the same boiling point
B. A boils at a lower temperature than B
C. B will not boil
D. B boils at a lower temperature than A
E. None of these.
(from the practice midterm for midterm 2
Do we need to know the structures of all the polymers given in table 12.5? Thanks.
ReplyDeleteQuiz 3, question 5
ReplyDeleteOf the compounds below, __________ has the smallest ionic separation.
Student Response Value
A. RbF
B. K2S
C. KF
D. SrBr2
E. RbCl
why is it KF not K2S?
From quiz 5-8 i can't see the answers or what i posted, it only shows whether i got the question correct or not. How do i find the answers?
ReplyDeleteIf given PH3, how are we supposed to know that it was not a polar molecule (therefore no dipole-dipole)without the electronegativity values? Also, in terms of electronegativitiy, which is more important, being higher or more to the left?
ReplyDeleteThanks
Hi Dr. Sirk,
ReplyDeleteI'm just wondering about naming molecules and the alphabetical order. I know that, for example, if you have an ethyl group substituent and two methyl group substituents you would write "dimethyl" before "ethyl" in the name, but what if you had 3 methyl groups, for example, so it was trimethyl, would you write that before or after the "ethyl" in the name i.e. is it the whole word or the root word without the suffix that you alphabetize.
Also, for the reactions, do we need to know the catalysts?
Thank you!
How does molecular weight affect intermolcular forces?
ReplyDeleteThanks
Hi Dr Sirk,
ReplyDeleteWhat do we need to know about ionic solids and their arrangement of atoms?
Thank you!!
Hello,
ReplyDeleteDo we name the alkynes by starting nearest to the triple bond, like the alkenes?
Hey!
ReplyDeleteDo we need to know the different names of addition reactions? (like bromonation)? If so, what are the ones we need to know?? What reaction names do wr need to know?
Thanks!!
Hello,
ReplyDeleteAre any molecules that have an O=R or O-R considered to be polar and have hydrogen bonding?
Thanks!!
Hi!!
ReplyDeleteAre condensation and dehydration reactions the same?
14. Which of the following descriptive combinations of atoms in a bond and type of bond is CORRECT?
ReplyDeletei. CsF, polar covalent iv. CF4, ionic
ii. F2, nonpolar covalent
iii. ICl, polar covalent
A. i B. i and ii C. ii and iii
D. ii and iv E. iv
could you explain the answer to this please?
thanks!
16. Which one of the following responses contains the correct order (from largest to smallest) of effective nuclear charge (Zeff)?
ReplyDeleteA. Li > Be > B
B. C > F > Na
C. Na > Be > Li
D. B > Be > N
E. Al > Na> Mg
Answer C is correct.. but by following the periodic table trend for Zeff, isn't that wrong?
Chapter 12 is 12.1-12.3 and 12.6
ReplyDeleteWith focus on the following pages:
12.1 (all) 12.2 (all) 12.3 484-485,488, 489,492, 12.6(all)
You said earlier that these are the readings for Chapter 12 but they don't make sense for the Tenth Edition textbook... Could you please clarify which pages in the Tenth Edition are included on the final exam?
Thank you!!
what does isobutyl and sec-butyl look like?
ReplyDeletewill we have to name structures with functional groups in them?
ReplyDeleteWhere are the review sheets that there were not enough of in the second review session today? You said they were going to on the website to print out? Thanks!
ReplyDeleteRe: Question 4 from quiz 8
ReplyDeleteA solid has a very high melting point, great hardness, and poor electrical conduction. This is a(n)
__________ solid.
a. covalent network
b. ionic
c. metallic
d. molecular
e. metallic and covalent network
Answer: Thanks for the clarification. There is a table on page 494 of the text that should be used. Ionic compounds are generally brittle, as opposed to hard so covalent networks bonding is the correct answer.
Re: Earlier you said we don't need to know the Silicon Chip or Semiconductor LED sections, but then you said pages 489 and 492 (which are on these two topics) are included. Do we need to know it?
Answer: Nope they are not covered, but there is still some useful concepts in the readings.
Re: Hi Dr. Sirk,
In regards to the second midterm, written question #4 c, how would you discard the less stable resonance structure - or better said, how do you know that it would be less stable?
Thank you!
Answer: Compounds are more stable is a) there are small (or no) formal charges and if there are formal charges b) the most electronegative atom has the most negative formal charge. Please note this not stable versus unstable per se, but a gradient of stability to consider for the valid Lewis structure. In this case the less stable compound (with a double bond to the Cl) has 4 formal charges, while the other have only two (all charges are +1 or -1). You’re welcome
Re: 10. If one compares compound A composed of nonpolar molecules with compound B composed of polar molecules, and both molecules have the same molecular formula then it is true that:
A. both compounds have the same boiling point
B. A boils at a lower temperature than B
C. B will not boil
D. B boils at a lower temperature than A
E. None of these.
(from the practice midterm for midterm 2
Answer: B (A boils at a lower temperature than B)
If the molecular weight is the same the London dispersion forces are the same and can be ignored for comparison forces. Therefore the molecule that is polar and therefore has dipole/dipole interactions has the higher boiling point.
Re:Do we need to know the structures of all the polymers given in table 12.5? Thanks.
Answer: No, but if given the monomers, you should be able to come up with the polymers and given the polymer structure, you should come up with the monomers and the correct reactions.
Re:
Of the compounds below, __________ has the smallest ionic separation.
Student Response Value
A. RbF
B. K2S
C. KF
D. SrBr2
E. RbCl
why is it KF not K2S?
Re: F- is smaller than S2-
Re: From quiz 5-8 i can't see the answers or what i posted, it only shows whether i got the question correct or not. How do i find the answers?
Answer : The answers are posted http://web.uvic.ca/~chem101/quizzes.html
Re: If given PH3, how are we supposed to know that it was not a polar molecule (therefore no dipole-dipole)without the electronegativity values? Also, in terms of electronegativitiy, which is more important, being higher or more to the left?
ReplyDeleteThanks
Answer: You would need the electronegativity values (2.20 and 2.19). The data sheets vary depending on the exam (I am assuming this was an exam question). As for left-right versus up-down, it depends where in the PT you are looking.
Re: I'm just wondering about naming molecules and the alphabetical order. I know that, for example, if you have an ethyl group substituent and two methyl group substituents you would write "dimethyl" before "ethyl" in the name, but what if you had 3 methyl groups, for example, so it was trimethyl, would you write that before or after the "ethyl" in the name i.e. is it the whole word or the root word without the suffix that you alphabetize.
Also, for the reactions, do we need to know the catalysts?
Thank you!
Answer: The base substituent is considered for alphabatization, so ethyl before methyl and ethyl before dimethyl. Yes, you should know the catalysts.
Re: How does molecular weight affect intermolcular forces?
Thanks
Answer: For London dispersion forces, they increase with molecular weight, for other forces, it has no effect. Welcome!
do polyethylene and ethane react differently in reactions? are they the same thing?
ReplyDeleteRe:Hi Dr Sirk,
ReplyDeleteWhat do we need to know about ionic solids and their arrangement of atoms?
Thank you!!
Answer: That they form ordered crystals and the structure will depend on charge and ion size. Actual structures are not required.
Re:Do we name the alkynes by starting nearest to the triple bond, like the alkenes?
Answer: Yes.
Hey!
Do we need to know the different names of addition reactions? (like bromonation)? If so, what are the ones we need to know?? What reaction names do wr need to know?
Thanks!!
Not the names, just the reactions. Though you should know the general terms hydrolysis and condensation.
Re: Hello,
Are any molecules that have an O=R or O-R considered to be polar and have hydrogen bonding?
Thanks!!
Answer: Yes, carboxylic acids have a C=O and can hydrogen bond through the C-O-H. Alcohols have C-O-H and also hydrogen bond
Re: Hi!!
Are condensation and dehydration reactions the same?
Answer: Yes
Re: 14. Which of the following descriptive combinations of atoms in a bond and type of bond is CORRECT?
i. CsF, polar covalent
ii. F2, nonpolar covalent
iii. ICl, polar covalent
iv. CF4, ionic
A. i B. i and ii C. ii and iii
D. ii and iv E. iv
could you explain the answer to this please?
thanks!
Answer: CsF-ionic (metal non-metal), F2-non polar covalent (same non non-metal atoms), ICl-polar covalent (different non-metals), CF4-polar covalent(different non-metals),. So ii and iii are correct
16. Which one of the following responses contains the correct order (from largest to smallest) of effective nuclear charge (Zeff)?
A. . Li > Be > B
B. C > F > Na
C. Na > Be > Li
D. B > Be > N
E. Al > Na> Mg
Answer C is correct.. but by following the periodic table trend for Zeff, isn't that wrong?
Zeff increases as one moves from left to right and down the PT.
A. Li > Be > B --- B>Be>Li (so wrong)
B. C > F > Na -- F>C, unsure about relative position of Na (wrong due to C vs F)
C. Na > Be > Li-- Na>Li, Be>Li, unsure about Be ve Na
D. B > Be > N - N>B>Be (so wrong)
E. Al > Na> Mg - Al>Mg> Na (so wrong)
This question is answered by eliminating wrong answers and accepting the only one without an error (though it has an uncertainty in it)..
Re: You said earlier that these are the readings for Chapter 12 but they don't make sense for the Tenth Edition textbook... Could you please clarify which pages in the Tenth Edition are included on the final exam?
Thank you!!
I don’t have a 10th edition text. Sections 12.1-12.2 (up to p. 501), 12.5. were in the original readings, but liquid crystals and superconductors are not included anymore. So polymers and semiconductors.
Re:what does isobutyl and sec-butyl look like?
Answer: For molecular shapes, it’s easier to Google the name using image search than for me to describe them.
Re:will we have to name structures with functional groups in them?
Answer: While this is a good question I already answered it twice in these comments.
Re: Where are the review sheets that there were not enough of in the second review session today? You said they were going to on the website to print out? Thanks!
Answer
http://web.uvic.ca/~asirk/
and
http://web.uvic.ca/~asirk/overview.htm
Re: do polyethylene and ethane react differently in reactions? are they the same thing?
ReplyDeleteAnswer: They are both alkanes so would react similiarly in that fashion, but polethylene is composed of thousands of C atoms and ethane is composed of 2 C atoms.
I don't understand Sample exercise 25.6 (10th Ed.) at all. I don't know why the molecule splits where it does or adds the H and O ions in the locations it does. Are there rules to this? What am I missing?
ReplyDeleteHello,
ReplyDeleteSo if the molecular weight was increased for a London dispersion, why is that causing an increase in the polarizability?
Thanks!!
Hey,
ReplyDeleteWhat how can I tell what type of crystal ZrO2 is? What are the general rules to tell?
Thanks!!
Also, what type would Kr be?
ReplyDeleteThanks!!
Hello,
ReplyDeleteFor the tutorials on Polymers, the first one says that one of the functional groups in the polymer is an aromatic ring, while the other is an amide.
I thought the functional groups were those branching off of the "back bone".. Why are the functional groups not amines and carboxylic acids? These are what bond to form the polymer.
Also, for the formation of carboxylic acids, I know there are two steps. Would we need to show both of the steps? What does the oxidation do to the molecules?
I am having a hard time with the reactions between functional groups, etc. Is there any way you could post practice questions, or recommend a good site that has practice for this?
Thanks!
Hey there,
ReplyDeleteOn the Aug. 2009 exam, Q. 13:
Which of the following would de-colourize an orange bromide solution?
A. hexane
B. diethylether
C.3-methylheptane
D.2,2,3-triethyloctane
How are we supposed to know this?
Q. 20. There is a picture of a polymer shown, and it asks for the name. Is it a polyester, as there are many ester linkages in it?
Q.29 asks about trends in the melting points of transition metals. Do we need to know this?
Q. 20 asks: Which would give an aldehyde when oxidized with a suitable oxidizing agent?
I know that an alcohol oxidizes to an aldehyde, but in the answer there is both CH3-OH and CH3-C(CH3)2-OH ... are these not both alcohols??
One of the written questions asks to draw out 3-ethyl-2,3-dimethylbutane, then asks for the proper IUPAC name.. would this be 2,3,3-trimethylpentane?
Also in the written, a 6-carbon ring is shown with only one double bond, then shows the addition of a Br2... it asks for the products. I am not sure if this is a substitution reaction or not, as those were only said to happen with the aromatics, which are benzene rings..
Also in this section of the written it shows a C3H8 + O2 then asks for the product with a spark as the catalyst.. what is this type of reaction?
Also, we are asked to draw an azide (N3-) molecule with all of its resonance structures, then asked to chose the one(s) that contribute the most..one of the resonance has (-1,-1,+1) charges, while the other two have (-2, +1) .. which is more preferred? Having three small charges, or two charges, one of which is larger?
Finally, when naming, where do we fit in the chloro-, bromo, etc. And do we need to know how to name the molecules based on their functional groups (ie. ethers end with ether, alcohols end with ol, etc.)
Finally, pg. 996 in edition 9, sample exercise 25.4 names the (a) picture as 4-methy-cis-2-heptane .. since when does the cis- occur within the name? Shouldn't it be: cis-4-methyl-2-heptane?
Or is the cis/trans supposed to show up directly before naming the double/triple bond?
Thanks!!
Also, where did we learn that Neon condenses to form a liquid at 27K because of London Dispersion forces?
The electron configuration [Kr]4d10 represents __________.
ReplyDeleteA. Sn+2
B. Sr+2
C. Te+2
D. Ag+1
E. Rb+1
why Ag+1 and not Sn+2?
(Quiz 4)
If you are asked how many isomers a molecule has, does the molecule itself count?
ReplyDeleteFor example, pentane
In which of the following molecules is hydrogen bonding likely to be the most significant component of the total intermolecular forces?
ReplyDeleteA. CH4
B. C5H11OH
C. C6H13NH2
D. CH3OH
E. CO2
(Quiz 8)
I understand that CH4 and CO2 do not contribute but why do C5H11OH and C6H13NH2 not?
What are the factors that effect Boiling point and melting point?
ReplyDeleteEX:List the correct order of metling point from highest to lowest for Benzene,toluene and phenpol.
Thanks.
#1. Why doesn't HI and H2S have ion-dipole intermolecular forces? can HI not break into H+ and I- and bond with the polar H2S?
ReplyDelete#2. Why are large molecules particularly polarizable regardless of polarity? how is a non-polar large molecule polarizable?
#3. A question on quiz 8 asked how many chiral centers are in CH3CHClCH2CH2CHBrCH3 and the answer was 2, but I though a chiral center required 4 different substituents coming off the carbon? doesnt this molecule have carbon bonded to 2 C's, a H and a halogen....only 3 different substituents.
thanks
when drawing lewis structures how can you tell if the pi bonds are delocalized?
ReplyDeletethanks
How do you know what shape a molecule will take? for example how do you know ClF3 is t-shaped and not trigonal planar or trigonal pyramidal.
ReplyDeleteWhy is a T-shaped molecule like BrF3 polar when XeF2 is non-polar? they are both trigonal bipyramidal
ReplyDeletewhy are the O-H bonds in H2O more polar than the Se-H bonds in SeH2?
ReplyDeleteis it because of hydrogen bonding? My first thought was that H and Se and farther apart.. does that apply to polarity at all?
Re:So if the molecular weight was increased for a London dispersion, why is that causing an increase in the polarizability?
ReplyDeleteAnswer: The polarizability increase is actually due to an increase in the size of the electron cloud. It is the electron cloud itself that becomes polarized (by a distortion of the shape). As the number of protons increase (molecular weight) the number of electrons will also increase and therefore the electron cloud also increases.
Re: Hey,
What how can I tell what type of crystal ZrO2 is? What are the general rules to tell?
Answer: Ionic: bonding between a non metal and a metal. You do not need to know the exact crystal structure
Re:Also, what type would Kr be?
Answer: Kr would be a molecular solid, as the bonding between the atoms is Vander Waals (LDF to be exact)
Re: For the tutorials on Polymers, the first one says that one of the functional groups in the polymer is an aromatic ring, while the other is an amide.
I thought the functional groups were those branching off of the "back bone".. Why are the functional groups not amines and carboxylic acids? These are what bond to form the polymer.
Answer: Functional groups are anything in an organic molecule that is not a C-C or C-H single bond. They are places on a molecule that can react, but don’t actually need to.
Amines and carboxylic aids would not be functional groups in the polymer because they aren’t in the polymer (the resulting amides and esters would be). They would be counted as functional groups in the monomers.
Re: Also, for the formation of carboxylic acids, I know there are two steps. Would we need to show both of the steps? What does the oxidation do to the molecules?
Answer: Yes, you need to know that oxidation of the alcohol gives an aldehyde and oxidation of the aldehyde gives a carboxylic acid. The oxidation introduces O and/or removes H.
Re: I am having a hard time with the reactions between functional groups, etc. Is there any way you could post practice questions, or recommend a good site that has practice for this?
Answer: The lecture notes contain the general reactions you need to know. Try rewriting those and anywhere it says “R”, add a methyl group. Then replace with a ethyl group and repeat. The text has god questions and you can rewrite them by changing the R group.. Do the ones within the text as well. It is worth noting there are only 6 overall reactions. Combustion, Addition to a multiple bond, Substitution on an aromatic, Oxidation of alcoholcarboxylic acids, formation of ester, formation of amide. All others are variations and back reactions of those.
Hey there,
On the Aug. 2009 exam, Q. 13:
Which of the following would de-colourize an orange bromide solution?
A. hexane
B. diethylether
C.3-methylheptane
D.2,2,3-triethyloctane
How are we supposed to know this?
Answer: Is that the complete question? Can you please double check? We did not cover any reactivity with ethers and we would require a double bond to do any other reactions.
Re: Q. 20. There is a picture of a polymer shown, and it asks for the name. Is it a polyester, as there are many ester linkages in it?
Answer: Sorry, I can’t answer this one, as I don’t actually have a copy of the exam.
Re: Q.29 asks about trends in the melting points of transition metals. Do we need to know this?
No
Q. 20 asks: Which would give an aldehyde when oxidized with a suitable oxidizing agent?
ReplyDeleteI know that an alcohol oxidizes to an aldehyde, but in the answer there is both CH3-OH and CH3-C(CH3)2-OH ... are these not both alcohols??
Answer, they are both alcohol, but one will give an aldehyde and the other would give a ketone when oxidised.
Re: One of the written questions asks to draw out 3-ethyl-2,3-dimethylbutane, then asks for the proper IUPAC name.. would this be 2,3,3-trimethylpentane?
Answer: 2,2,3-trimethylpentane
Also in the written, a 6-carbon ring is shown with only one double bond, then shows the addition of a Br2... it asks for the products. I am not sure if this is a substitution reaction or not, as those were only said to happen with the aromatics, which are benzene rings..
Re: Also in this section of the written it shows a C3H8 + O2 then asks for the product with a spark as the catalyst.. what is this type of reaction?
Answer: Combustion (products will be CO2 and water)
Re: Finally, when naming, where do we fit in the chloro-, bromo, etc. And do we need to know how to name the molecules based on their functional groups (ie. ethers end with ether, alcohols end with ol, etc.)
Answer: Chloro and bromo follow the same rules as methyl and ethyl. All substituents are considered under the same rules.
Re: Also, where did we learn that Neon condenses to form a liquid at 27K because of London Dispersion forces?
Answer: Neon is non-polar. Therefore the only intermolecular forces available are London Dispersion forces. You would not need to know the exact temperature BUT if given the condensation temperature of Ar and Ne, you should know that Ne is between those two.
Re: The electron configuration [Kr]4d10 represents __________.
A. Sn+2
B. Sr+2
C. Te+2
D. Ag+1
E. Rb+1
why Ag+1 and not Sn+2?
(Quiz 4)
Answer: Sn is [Kr]5s2 4d10 5p2 so Sn+2 would be [Kr]5s2 4d10. Sn4+ would have that configuration.
Re: If you are asked how many isomers a molecule has, does the molecule itself count?
For example, pentane
Answer: Yes, every configuration of the molecule counts.
Dec. 2009 practice exam
ReplyDeleteQuestion 28
Benzene, toluene and phenol are all solids at -50 degrees, the correct order for melting points from highest to lowest would be:
answer: phenol>benzene>toluene
why is this?
Dec 2008 exam
ReplyDeleteQ.1
If one mole of identical photons has a total energy of 845kJ, what is the frequency associated with these photons?
The answer says 2.12x10^15
I calculated 1.28x10^39 though.. where did I go wrong?
based on MO or band theories of metal bonding, which of the following metals would you expect to have a higher melting point than iron?
ReplyDeletea. cadmium
b. nickel
c. chromium
d. copper
e. calcium
thanks
Dec 2008 final
ReplyDeleteQuestion 26.
Of the molecules CO2, NH4+ and CO3^2-, which has/have delocalized pi bonding?
the answer is CO3^2- only
why not CO2?
How do you tell if an element or compound forms a molecular solid or a network covalent solid?
ReplyDeleteDo we need to know which catalysts are needed for each reaction?
ReplyDeleteIn one of the written on the 2009 exam, it asks for all of the structural and geometric isomers for butene.. 2-methylpropene is one of the answers.. does this mean that for structural isomers the root words may be different, but if the number of carbons are the same, then it is okay?
ReplyDeleteIs this because structural isomerism refers to the same molecular formula? So the substituents would be counted in this?
Thanks!
A semiconductor laser in a CD player has an output wavelength of 780 nm and power level of 1.0 x 104 J s:r. How many photons strike the CD surface during the playing of a CD of 69 minutes ih length?
ReplyDelete1 photon = hc/lambda = (6.63 x 10^-34)(3 x 10^8) / (780 x 10^9 m/nm) ... this last part had me thrown off.. it is saying that there are 10^9 m per nanometer.. shouldn't it be 780 x 10^9 nanometers per meter?
I have noticed that there are quite a few errors in the exams that I bought from the Chem Society.. it is really screwing me up in my studying, because I can never tell when I am right or wrong..
why does NH3 have a higher boiling point than PH3?
ReplyDelete(final exam Dec. 2007 Question 17)
In the practice exercise for 9.3 in the 11th ed. why is the bond angle for C-C-C 180? wouldn't it be slightly greater than 109.5 because there are 4 domains on the central carbon making it tetrahedral and then the large triple bond makes it slightly larger?
ReplyDeleteAre there no dipole dipole forces if there is H-bonding? or are the H-bonding forces just focused on because they are stronger?
ReplyDeletefrom the 2007 exam, question 4d longer answer says that in order to dissolve CsI in H20, hydrogen bonds must be overcome
ReplyDeleteDoes this mean that we must consider the water and not just that compound?
Question 6c longer answer final Dec 2007
ReplyDeleteUse the average bond energies on the data sheet to calculate the enthalpy change when one mole of vinyl chloride polymerizes to form polyvinylchloride.
the answer says that one carbon-carbon double -bond is broken and 2 carbon-carbon single bonds are formed.
Wouldn't it be 2 carbon-carbon double bonds broken and 3 carbon-carbon single bonds formed?
..
ReplyDeleteAnonymous said...
Re: In which of the following molecules is hydrogen bonding likely to be the most significant component of the total intermolecular forces?
A. CH4
B. C5H11OH
C. C6H13NH2
D. CH3OH
E. CO2
(Quiz 8)
I understand that CH4 and CO2 do not contribute but why do C5H11OH and C6H13NH2 not?
Answer: C5H11OH and C6H13NH2 have hydrogen bonding, as does CH3OH. The key is which molecule has hydrogen bonding as its most significant component. So all molecules have LDF and the larger molecules have more than smaller. Therefore hydrogen bonding will be a larger proportion of the total intermolecular bonding. Also O-H hydrogen bonding will be stronger than N-H.
Anonymous said...
Re:What are the factors that effect Boiling point and melting point?
EX:List the correct order of metling point from highest to lowest for Benzene,toluene and phenpol.
Answer: Packing and intermolecular forces.
Melting point is phenol (hydrogen bonding)>benzene (good packing and LDF)>toluene (LDF)
Boiling point is phenol (hydrogen bonding) > toluene (LDF is greater due to higher molecular weight) > benzene (LDF, no packing bonus in a liquid)
Anonymous said...
Re: #1. Why doesn't HI and H2S have ion-dipole intermolecular forces? can HI not break into H+ and I- and bond with the polar H2S?
Answer: It would be possible. The system would need to be significantly cooled as H2S is a gas at room temperature.
Re: #2. Why are large molecules particularly polarizable regardless of polarity? how is a non-polar large molecule polarizable?
The electron cloud in a larger molecule is larger and the polarizability is directly proportional to the size of the electron cloud.
Re:#3. A question on quiz 8 asked how many chiral centers are in CH3CHClCH2CH2CHBrCH3 and the answer was 2, but I though a chiral center required 4 different substituents coming off the carbon? doesnt this molecule have carbon bonded to 2 C's, a H and a halogen....only 3 different substituents.
thanks
Answer: The two C are different. One is a methyl group and the other is 4 C chain.
Anonymous said...
Re: when drawing lewis structures how can you tell if the pi bonds are delocalized?
thanks
Answer: If you can draw multiple valid lewis structures (resonance structures) with a multiple bond in various places in the molecule, the pi bonds are delocalised.
Anonymous said...
Re:How do you know what shape a molecule will take? for example how do you know ClF3 is t-shaped and not trigonal planar or trigonal pyramidal.
Answer: You must determine the electronic geometry first (in this case trigonal bypiramidal) and then put the lone pairs (2) in the positions with the most space (equatorial) and the remaining atoms form a T shaped molecule.
Anonymous said...
Re: Why is a T-shaped molecule like BrF3 polar when XeF2 is non-polar? they are both trigonal bipyramidal
Answer: When considering polarity, you do not need to consider the lone pairs (except as they influence the electronic and molecular geometry). The polarity is determined by the molecular geometry and a T shaped molecule will be polar and a linear one will not be.
Anonymous said...
Re: why are the O-H bonds in H2O more polar than the Se-H bonds in SeH2?
is it because of hydrogen bonding? My first thought was that H and Se and farther apart.. does that apply to polarity at all?
Answer: O is more electronegative than Se. Recall that electronegativity increases to the right and up. So O-H is more polar and therefore can participate in hydrogen bonding.
Re: Dec. 2009 practice exam
ReplyDeleteQuestion 28
Benzene, toluene and phenol are all solids at -50 degrees, the correct order for melting points from highest to lowest would be:
answer: phenol>benzene>toluene
why is this?
Answer: Just answered this one in previous batch of questions
Re: Dec 2008 exam
Q.1
If one mole of identical photons has a total energy of 845kJ, what is the frequency associated with these photons?
The answer says 2.12x10^15
I calculated 1.28x10^39 though.. where did I go wrong?
Answer: You need to divide by Avogadro’s number to get the energy in a single photon and the calculate the frequency.
Re: based on MO or band theories of metal bonding, which of the following metals would you expect to have a higher melting point than iron?
a. cadmium
b. nickel
c. chromium
d. copper
e. calcium
thanks
Answer: Not tested this year.
Re: Dec 2008 final
Question 26.
Of the molecules CO2, NH4+ and CO3^2-, which has/have delocalized pi bonding?
the answer is CO3^2- only
why not CO2?
Answer: CO2 has only one valid Lewis structure and therefore does not have resonance structures.
Re:How do you tell if an element or compound forms a molecular solid or a network covalent solid?
Answer: If they are small discrete molecules, it will be a molecular solid (Intermolecular forces are Van der Waals). If it is a continuous network,it is a network covalent solid (intermolecular forces and intramolecular forces are covalent)
Re:Do we need to know which catalysts are needed for each reaction?
Answer: Yes
Re: In one of the written on the 2009 exam, it asks for all of the structural and geometric isomers for butene.. 2-methylpropene is one of the answers.. does this mean that for structural isomers the root words may be different, but if the number of carbons are the same, then it is okay?
ReplyDeleteIs this because structural isomerism refers to the same molecular formula? So the substituents would be counted in this?
Thanks!
Answer: Yes, A structural isomer has the same chemical formula but different connectivity. It has nothing to do with the naming.
Re: A semiconductor laser in a CD player has an output wavelength of 780 nm and power level of 1.0 x 104 J s:r. How many photons strike the CD surface during the playing of a CD of 69 minutes ih length?
1 photon = hc/lambda = (6.63 x 10^-34)(3 x 10^8) / (780 x 10^9 m/nm) ... this last part had me thrown off.. it is saying that there are 10^9 m per nanometer.. shouldn't it be 780 x 10^9 nanometers per meter?
Answer: Yup (or 780*10^-9 m/nm)
Re: I have noticed that there are quite a few errors in the exams that I bought from the Chem Society.. it is really screwing me up in my studying, because I can never tell when I am right or wrong..
Answer: Join the Chemistry society and offer to help with exam answer writing.
Re: why does NH3 have a higher boiling point than PH3?
(final exam Dec. 2007 Question 17)
Answer: NH3 has hydrogen bonding and PH3 has dipole-dipole.
Re: In the practice exercise for 9.3 in the 11th ed. why is the bond angle for C-C-C 180? wouldn't it be slightly greater than 109.5 because there are 4 domains on the central carbon making it tetrahedral and then the large triple bond makes it slightly larger?
December 8, 2010 5:53 PM
Re: Are there no dipole dipole forces if there is H-bonding? or are the H-bonding forces just focused on because they are stronger?
Answer: H-bonding is a stronger form of dipole-dipole bonding.
Re: from the 2007 exam, question 4d longer answer says that in order to dissolve CsI in H20, hydrogen bonds must be overcome
Does this mean that we must consider the water and not just that compound?
Answer: Sorry, I can’t answer that with the information given.
Re: Use the average bond energies on the data sheet to calculate the enthalpy change when one mole of vinyl chloride polymerizes to form polyvinylchloride.
the answer says that one carbon-carbon double -bond is broken and 2 carbon-carbon single bonds are formed.
Wouldn't it be 2 carbon-carbon double bonds broken and 3 carbon-carbon single bonds formed?
Answer: Each molecule of vinyl chloride has one double bond and transforms into two single bonds (one where the original double bond was and one to the adjoining monomer). This may be easier to visualize if you start with about 4 or 5 vinyl chlorides and add them together one by one
.
ReplyDeleteRe: Finally, pg. 996 in edition 9, sample exercise 25.4 names the (a) picture as 4-methyl-cis-2-heptane .. since when does the cis- occur within the name? Shouldn't it be: cis-4-methyl-2-heptane?
Or is the cis/trans supposed to show up directly before naming the double/triple bond?
Thanks!!
Answer: The second is correct (but would need to be heptene)
Re: Also, we are asked to draw an azide (N3-) molecule with all of its resonance structures, then asked to chose the one(s) that contribute the most..one of the resonance has (-1,-1,+1) charges, while the other two have (-2, +1) .. which is more preferred? Having three small charges, or two charges, one of which is larger?
Answer: Three small charges is more stable.
Re: I don't understand Sample exercise 25.6 (10th Ed.) at all. I don't know why the molecule splits where it does or adds the H and O ions in the locations it does. Are there rules to this? What am I missing?
Answer: The mechanism of reactions is not required.
---------------------------------------------
ReplyDeleteNOTICE: I think I am officially caught up. If I have missed your question, please repost. Questions posted before 9AM Thursday will be answered.
--------------------------------------------------
You sort of answered this question earlier, but can you tell from the molecular formula alone if something will be a network covalent solid or a molecular solid?
ReplyDeleteIn a fashion, yes. If the molecular formula shows you have a discrete molecule (ie something with less than 100 atoms total) you have a molecular solid. If the molecular formula is infinite (eg: Cn or C(infinity symbol) it's a network covalent solid. This is complicated because molecular solids are sometimes written as simply C. Also polymers are not considered network covalent solid but have very similar properties (but lack the ordered structure).
ReplyDeleteShort answer: If you can draw the entire discrete molecule on a single piece of paper, it's a molecular solid. (You couldn't draw all of diamond. You could draw enough for people to understand the structure, but the molecule itself is infinite)
REPOST:
ReplyDeleteRe: In the practice exercise for 9.3 in the 11th ed. why is the bond angle for C-C-C 180? wouldn't it be slightly greater than 109.5 because there are 4 domains on the central carbon making it tetrahedral and then the large triple bond makes it slightly larger?
December 8, 2010 5:53 PM
there wasn't an answer!
Hi, I have 2 questions:
ReplyDelete1) How would you determine whether S or N was ore electronegative?
2) How would you determine whether HCl or HBr is more polar?
Thanks!
REPOST
ReplyDeleteQ. 20 asks: Which would give an aldehyde when oxidized with a suitable oxidizing agent?
I know that an alcohol oxidizes to an aldehyde, but in the answer there is both CH3-OH and CH3-C(CH3)2-OH ... are these not both alcohols??
Answer, they are both alcohol, but one will give an aldehyde and the other would give a ketone when oxidised.
Question: But how do we know which one will give a ketone or aldehyde?
Also, you say with an oxidation an oxygen is added or hydrogen taken away.. how are we supposed to know which, and how do we know where to put it?! You say we need to know the oxidation of an alcohol to a carboxylic acid, but I will not know what the middle man looks like, or where to add the carbon to the carboxylic acid!
Re: One of the written questions asks to draw out 3-ethyl-2,3-dimethylbutane, then asks for the proper IUPAC name.. would this be 2,3,3-trimethylpentane?
Answer: 2,2,3-trimethylpentane
Question: I tried several times to get a 2,2,3 , but I could not, because the only way to get the longest chain would be to start from the end of the ethyl chain, or from the start of the original and in both situations it is a 2,3,3.. could you please describe how your molecule looked?
Also in the written, a 6-carbon ring is shown with only one double bond, then shows the addition of a Br2... it asks for the products. I am not sure if this is a substitution reaction or not, as those were only said to happen with the aromatics, which are benzene rings.
This was not answered... are we supposed to infer that if it is a cycloalkene ring that the double bond will be broken and that the two molecules will be attached to the carbons?
Which of the following would de-colourize an orange bromide solution?
A. hexane
B. diethylether
C.3-methylheptane
D.2,2,3-triethyloctane
This was the exact wording, sorry!
Finally, as with the chromo-bromo, would it the the same with nitro-, iodo-, hydroxyl- , fluoro- .. (ie. 2,3-dibromohexene, or 4-nitropentane..)
Thank you!
Re: In the practice exercise for 9.3 in the 11th ed. why is the bond angle for C-C-C 180? wouldn't it be slightly greater than 109.5 because there are 4 domains on the central carbon making it tetrahedral and then the large triple bond makes it slightly larger?
ReplyDeleteDecember 8, 2010 5:53 PM
there wasn't an answer!
Answer: With triple bond off the C, the C would be sp hybridised and therefore linear. The C has only 2 electron domains (one is a triple bond and one is a single bond). A linear hybridisation would have 180 degree bond angle.
How do we know that SbH3 has a higher boiling point than NH3?
ReplyDeleteThanks!
Re: Hi, I have 2 questions:
ReplyDelete1) How would you determine whether S or N was ore electronegative?
Answer: Electronegativity increases to the right and up. This one is tricky because N is above S, but S is to the right. Then you can recall that only three elements are considered electronegative enough to facilitate H bonding (O,F, and N). Therefore N must be more electronegative than S.
2) How would you determine whether HCl or HBr is more polar?
Answer:This one is easier. H is less electronegative than either, so you just need to determine which of Cl and Br is more electronegative. Cl is above Br and therefore more electronegative.
Thanks!
You’re welcome
Anonymous said...
REPOST
Q. 20 asks: Which would give an aldehyde when oxidized with a suitable oxidizing agent?
I know that an alcohol oxidizes to an aldehyde, but in the answer there is both CH3-OH and CH3-C(CH3)2-OH ... are these not both alcohols??
Answer, they are both alcohol, but one will give an aldehyde and the other would give a ketone when oxidised.
Question: But how do we know which one will give a ketone or aldehyde?
Answer: Draw out the molecules. Pay attention to the C with the C-OH bond. One (methanol) has a C with 3 H off it and a –OH. Upon oxidation, there will be a C with =O and 2 bonds to H. This is an aldehyde.
The second molecule starts with a C bonded to OH and the other 3 bonded to C. Upon oxidation, one would get a C with =O and bonded to two carbons. This is a ketone. (This reaction would also be harder to do)
Re: Also, you say with an oxidation an oxygen is added or hydrogen taken away.. how are we supposed to know which, and how do we know where to put it?!
Answer: Yes. From an alcohol to aldehyde, you lose 2 H (one off the C, one off the H). From an aldehyde to a carboxylic acid, you gain one O (that becomes –OH).. Once you know what the products are, you will know where to put it.
Re: You say we need to know the oxidation of an alcohol to a carboxylic acid, but I will not know what the middle man looks like, or where to add the carbon to the carboxylic acid!
Answer: The middle product is an aldehyde. You don’t add any C to make the carboxylic acid. The C that had the –OH off of it will become the C with =O and –OH off it.
Question: I tried several times to get a 2,2,3 , but I could not, because the only way to get the longest chain would be to start from the end of the ethyl chain, or from the start of the original and in both situations it is a 2,3,3.. could you please describe how your molecule looked?
Answer: Sorry, typo, yes 2,3,3 is correct.
Also in the written, a 6-carbon ring is shown with only one double bond, then shows the addition of a Br2... it asks for the products. I am not sure if this is a substitution reaction or not, as those were only said to happen with the aromatics, which are benzene rings.
This was not answered... are we supposed to infer that if it is a cycloalkene ring that the double bond will be broken and that the two molecules will be attached to the carbons?
Answer: Yes, it is treated just like a double bond because that is what it is.
Which of the following would de-colourize an orange bromide solution?
A. hexane
B. diethylether
C.3-methylheptane
D.2,2,3-triethyloctane
This was the exact wording, sorry!
Answer: OK, The answerwould be B because it is the only one with a functional group. You know that alkanes do not react (except in combustion) so this question would be approached as “eliminate the wrong answers”. If there were an alkene, that would be the better answer, so I needed to check that the wording was correct. There was another eliminate the wrong answers related to ionization energy earlier in the notes.
Re: Finally, as with the chromo-bromo, would it the the same with nitro-, iodo-, hydroxyl- , fluoro- .. (ie. 2,3-dibromohexene, or 4-nitropentane..)
Thank you!
Answer: Yes, the naming rules are the same.
You’re welcome.
Re: How do we know that SbH3 has a higher boiling point than NH3?
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