Thursday, December 5, 2013

Exam revision

Here's some more practice problems for you to try: one exam from 2010, and another compilation from earlier than that (note: there is an error in Q38, the formula should be C4H8O, not C4H10O.

I recorded myself solving the compilation. The picture is a little fuzzy and the sound not great, but if you get stuck on a particular question and want to know how I got the answer, just skip through the video until you find it. I went through problems at roughly 1/minute. I circled the wrong answer in Q4 AND Q7 (the answers are right in the key); sorry! See how easy it is to make silly mistakes when you're rushing?

http://www.youtube.com/watch?v=JWyX5PAfEvc

Dr Briggs reports that answers to old exams are not posted for any course. I am of course happy to answer any questions you have during the review session, office hours, etc.

49 comments:

Anonymous said...

Has the Mastering Chemistry page for Chem 101 been closed? because I can't access it

Anonymous said...

Is the mastering Chemistry access gone for students? There is a lot of stuff on there worth studying from but I cant access any of it...

Scott McIndoe said...

It seems the MC end date for the course was set to Dec 7; I've changed it to Dec 14. Let me know if that fixes it or not, thanks.

Anonymous said...

yes it worked!

Anonymous said...

Its all good now, Thank you!

Anonymous said...

I'm 90% sure that the answer for question 4 of the video should be E but yet you wrote D, am I wrong?

Scott McIndoe said...

Yeah, it should be E, sorry (it's right in the answer key though). I think my explanation is OK, just not what I circled! Thanks for noticing.

Anonymous said...

The chemical formula of 38 should be c4h8o right? Since the oxygen would "take" 2 electrons away in the ketone that would otherwise be used for the hydrogen

Scott McIndoe said...

Oh, @%$#%^*! Yes. Sorry.

Anonymous said...

just wondering why Cr, Mo, W would have higher melting points than Ti, Zr, and Hf. I understand that filled bonding orbs increase melting points, and filled antibonding orbs decrease it, but (from the way I'm working it out), Ti, Zr, and Hf would have 2 val e' in bonding and no in antibonding..... (This is question 51 from winter 2012 exam)

Anonymous said...

for some reason I can't seem to find how many questions are on the final exam. i know you probably told us, but can you remind me please?

Scott McIndoe said...

601: Combine together the s and the d electrons in a single band that can accommodate 12 electrons, and it will make a lot more sense.
158: 65

Anonymous said...

Where could an answer key for the 2010 final be found?

Scott McIndoe said...

Dr Briggs reports that answers to old exams are not posted for any course. I am of course happy to answer any questions you have during the review session, office hours, etc.

Anonymous said...

looking at question 28, using the data sheet, i got -373 kJ/mol. could you please clarify? thanks!

Scott McIndoe said...

May have been constructed using slightly different values (average bond enthalpies depend on what bond energies you choose to average!).

Anonymous said...

How could Q14 be worded another way? I don't really get what it is saying.
And, for Q27, I could not hear why option B could not be the answer?

Anonymous said...

For: Which of the following molecules has the most polar bonds?
PF3, SF2, N2, SeBr2, CH4. Why is the answer CH4 and not PF3?

Scott McIndoe said...

930: You can measure a bond angle between any two atoms bonded to a central atom. Considering all the possible combinations, how many are 90°?
Because you haven't filled the orbital energy level diagram from the bottom up.
953: The answer is wrong. It should be PF3. Where was this?

Anonymous said...

Q.62 from the Dec 2012 final asks: If part of a LCD screen is heated, that part of the screen will go black. Why?

The answer says that it's because the nematic liquid crystal phase transforms into a smectic liquid crystal phase, which can't polarize light.

Can you explain? I thought heating a nematic LC would turn it back into normal liquid phase.

Scott McIndoe said...

You're right. The model answer you have is wrong.

Anonymous said...

It was in the 2012 exam Q15. Oh sorry the answer was D which was SeBr2 when PF3 is A.

Anonymous said...

If I failed the lab component of the course, would I have to retake the lecture as well?

Anonymous said...

for naming organic compounds in our finals, will we be given the entire molecule written out or could we also be asked to name the condensed structural formula of a molecule?

Anonymous said...

Will we need to know and use Slater's rule for finding the Zeff of certain electrons?

Anonymous said...

could you say that if you did pretty well for the attached compilation, that you are a little ready for the exam?

Anonymous said...

In the 2010 exam for question one the Uncertainty formula, which velocity do you used? The 10.0m/s?

Thanks!

Anonymous said...

Will we be expected to memorize/ recognize specific types of polymers on the exam (e.g. polyurethane)?

Anonymous said...

What is the total energy (in kJ) of a mole of photons of frequency 3.13 × 1011 s–1 ?

Would be answer be = 0.125? or 2.08x10^-25

Anonymous said...

Will you be posting the answer key to the 2012 practice final exam?

Scott McIndoe said...

532: OK
643: Yes
647: Maybe. It's MC, remember
805: No
817: don't get cocky
823: use the uncertainty, not the absolute value
902: Probably not
908: for 1 photon, E = hv. That's a very small number. Multiply by Avogadro's number, a very big number. I suspect 0.125.
1011: No

Anonymous said...

This is a question from mastering chemistry: Would solid metallic and ionic compounds have charged particles throughout it?

According to the answers only ionic compounds would. Why is that?

Anonymous said...

In your compilation solution video, I think you circled the wrong answer in question 7. You explained it well, but the answer should be D, not B. Is that correct?

Anonymous said...

What is the point of having both n-type and p-type semiconductors in solar cells? Why isn't just one type sufficient?

Anonymous said...

Why are the answers not posted for the final exams. Not having the answers we could be studying something completely wrong instead of understanding why we got it wrong and how to fix it. Is there anyway to get answers for them?

Anonymous said...

Would you be able to briefly explain number 7 on the 2010 exam?

Anonymous said...

I am wondering why on the first midterm version A number 26 has the answer E instead of B, isn't the atom more stable if it has a half filled or fully filled d. I am confused as to when the d gets half or fully filled and when it does not?

Scott McIndoe said...

1128: Metals are made of atoms, ionic compounds ions. But of course atoms themselves are made of charged particles (electrons, protons). Not the best question ever.
1221: Yes, sorry. Argh!
124: They kind of act as a one-way valve for electrons.
125: No, but I'm happy to answer questions on specific problems you are struggling with. Note that I posted a selection of questions with an answer key and an explained video solution - try that.
303: Always remove electrons from the highest principal quantum number first.
402: there were only 25 questions on that exam.

Anonymous said...

Do n-type and p-type dopants both increase the electrical conductivity of the solutions they are added to? Or is one more effective than the other in increasing conductivity?

Anonymous said...

In a hydrogen atom, how many unique sets of four quantum numbers, n, l, ml and ms can an electron have when n = 4 and ml = −1?
The wording is a little confusing, could you explain the answer please?

Anonymous said...

For question number 2 in end of Chapter 6 review questions, would the second name not be "TRANS-4-methyl-2-pentane"? the answer just says 4-methyl-2-pentane

Scott McIndoe said...

521: [semiconductors, not solutions] Yes.
530: Only the 4p, 4d and 4f orbitals can have ml = -1, and each of these 3 orbitals can hold 2 electrons, so the answer is 6.
532: Yes.

Anonymous said...

I commented at 402, I meant number 25 woopsies

Anonymous said...

For question 36 in this practice final http://web.uvic.ca/~chem101/C101Fall2012Exam.pdf , what is the correct answer?

Anonymous said...

623: The correct answer for 36 on the 2012 final is B.

Scott McIndoe said...

620: For ions, always remove electrons from the highest principal quantum numbers first, regardless of filling order. Transition metals never have any s electrons when they are cations, they are always just d^something.
623: B
838: Yes! Thanks.

Anonymous said...

I was gonna tell a chemistry joke, but all the good ones Argon :(

Anonymous said...

What are the two oxygen-containing functional groups on the left and on the right of Naproxen from the Dec 2012 final?

Anonymous said...

1050: The answer for 33 on the 2012 final is ether and carboxylic acid.