Tuesday, November 29, 2011

Review sessions, office hours, etc

Info about the final exam, including the review sessions, is here: http://web.uvic.ca/~chem101/Chem101PreExamInfofall2011.pdf

Friday's class will be mostly review material.

Dr Burford's review session is Friday December 2, 3:30-5:00pm - ECS 123
My review session is Saturday December 3, 10:00am to Noon – Sci B150.
Dr Briggs' review session is Monday December 5, 10:00am to 11:30am – Mac A144.

Any other review sessions advertised are NOT affiliated with the Department of Chemistry.

My office hours this week are Tue, Wed and Thur 2:30 - 4:30 pm.

88 comments:

Anonymous said...

Are the answers to the sample finals in the lab manual posted anywhere?

Scott McIndoe said...

I think ChemSoc are selling the Dec 2010 one. Otherwise, no.

Anonymous said...

Are either of the assignments or homework assignments on master chemistry actually for marks or just for practice?

Scott McIndoe said...

just for practice. Only the quizzes are graded.

Anonymous said...

Hello Dr.

-For chapter 3, section 4.
We said that if the value <.5, the bond is nonpolar, if it's between .5 and 2 it's polar covalent ect.. Does this refer to the electronegativity differences or to the dipole moment?

Scott McIndoe said...

EN difference

Anonymous said...

Just thought you would like to know, on ratemyproffessor you have all good comments! only prof i know of that has that

Anonymous said...

I have a question from the exam in the lab manual
I calculated the Zeff of aluminum to be +3, and the next question says that actual calculated charge is +4, and it asks to account for the difference between that and the one you calculated

Why is there a difference? Is it because the core electrons aren't completely effective in shielding?

Scott McIndoe said...

Yes, exactly.

Anonymous said...

Hello,
Could you go over the units in tomorrows session?
like for wavelength, energy ect?

Scott McIndoe said...

The units will come up in some of the examples, certainly.

Anonymous said...

How do you write the excited state configuration ?

Anonymous said...

You got way more than 20 showing up Sat morning because you're a great prof and we knew your session would be a big help- and it was! Thanks for a great semester! You rock!

Anonymous said...

Are we expected to know Haloalkanes from Chapter 7 for the final exam?

Scott McIndoe said...

Re: excited state configuration - basically, you just promote an electron - any electron - to a higher energy orbital that it was in originally.

Re: turnout - hey, thanks. Glad it was useful.

Re: haloalkanes - possibly. We do talk about fluoro, chloro, bromo, iodo substituents e.g. the product of Br2 addition to ethene is 1,2-dibromoethane, for example.

Anonymous said...

I have a lot of questions:

1.Could you explain the uncertainty equation? (change in x)(change in momentum) > h/4pi

2. What is the total energy in kJ/mole of a mole of photons of frequence v=3.13x10^11 hz?
Would the answer be .125kJ/mole? the answer key on this practice final says 125

3. An indium atom has 49 electrons. which subshell would experience the lowest zeff? wouldnt the answer be 5p because it is getting screened the most? answer key says 4d

4. groups F,Cl,Br and N, O, F would both have all members having negative electron affinities right?

5. Consider doping the semiconducting material germanium. Addition of which element would make germanium a better conductor. (Ga, P, As, Al, all of above) all of these would either turn it into a p-type or n-type semic so why is the answer key saying Al?

6.BeCl2 would see the central atom not obeying the octet rule. Why is this?

7. Considering likely intermolecular forces which one should have lowest boiling point. (dimethyl ether, ethanol, propane, ch3ch2sh, pentane) the answer key says its the alcohol which makes no sense. Would the answer be propane?

8. when methylamine and acetic acid are combined, the products will be water and methyamide? answere key says no reaction....

9.what will be the two monomers used in polythylene terephthalate

Sorry abou the list but i believe this answer key is erroneous and I just want to verify.

Scott McIndoe said...

I don't have a copy of the ChemSoc model answer, nor do I know what exam you're looking at, but I'll give it a shot...

1.Could you explain the uncertainty equation? (change in x)(change in momentum) > h/4pi

This equation allows you to predict the uncertainty in the momentum of a particle, provided you know the uncertainty in your measurement of its position (or vice versa).

2. What is the total energy in kJ/mole of a mole of photons of frequence v=3.13x10^11 hz?
Would the answer be .125kJ/mole? the answer key on this practice final says 125

E = h x nu x Avogadro's number will give the value in J/mole, so divide by 1000 to get kJ/mole. It sounds like it is possible that the model answer forgot the last step.

3. An indium atom has 49 electrons. which subshell would experience the lowest zeff? wouldnt the answer be 5p because it is getting screened the most? answer key says 4d

Yes, the answer should be whatever electrons are LAST when you write out the electron configuration from the PT, because these electrons are screened (at least partially) by the ones that come before.

4. groups F,Cl,Br and N, O, F would both have all members having negative electron affinities right?

No - N has a >0 EA, because of the unfavourability of pairing an electron in an already-occupied orbital.

5. Consider doping the semiconducting material germanium. Addition of which element would make germanium a better conductor. (Ga, P, As, Al, all of above) all of these would either turn it into a p-type or n-type semic so why is the answer key saying Al?

The answer should be all of the above.

6.BeCl2 would see the central atom not obeying the octet rule. Why is this?

Giving Be an octet requires it to carry a 2- formal charge and both Cls a +1 formal charge. Better to leave Be without an octet.

7. Considering likely intermolecular forces which one should have lowest boiling point. (dimethyl ether, ethanol, propane, ch3ch2sh, pentane) the answer key says its the alcohol which makes no sense. Would the answer be propane?

Propane is the correct answer.

8. when methylamine and acetic acid are combined, the products will be water and methyamide? answere key says no reaction....

You're right; the products are methylethanamide and water.

9.what will be the two monomers used in polythylene terephthalate

Poly*e*thylene terephthalate? They should be HOCH2CH2OH and HOOCC6H4COOH.

Sorry abou the list but i believe this answer key is erroneous and I just want to verify.

Yes, it seems you've found a lot of errors. Disclaimer: the professors have nothing to do with the preparation of the ChemSoc model answers!

Good luck in the exam.

Anonymous said...

Good morning!

How would you name an 9C alkane that has 2 methyl groups on carbon 2 and one methyl group on carbon 5?

Scott McIndoe said...

If 9C in total, then 2,2,5-trimethylhexane. If 9C in the longest chain, 2,2,5-trimethylnonane.

Anonymous said...

the quiz was not due sunday this time? oh no..

Anonymous said...

-CdS has a band gap of 2.4 . If large crystals of CdS are illuminated with ultraviolet light they emit light equal to the band gap energy. WHat color is the emitted light?

Anonymous said...

i think im missing the main point about boiling pts and melting pts.. i never know when they're high or low

Anonymous said...

Should we remember all the polymers in the book

Anonymous said...

how do you differentiate condensation polymers and addition polymers?

Scott McIndoe said...

Re: CdS. I assume the value is eV? If so, 1 eV = 1.60217646 × 10-19 joules (see data sheet), then use E = hc/lambda to find the wavelength and hence the colour.

Re: mp, bp. Generally, these depend on strength of intermolecular interactions, so use the relative order ionic > ion-dipole > H-bonding > dipole-dipole > dispersion. If dispersion only, compare total no. of electrons, and if these are the same, choose the one that has the highest surface area i.e. long and skinny rather than spherical.

Re: memorising polymer names - no, but you do need to be able to recognise functional groups.

Condensation polymers have functional groups in the backbone of the polymer, addition polymers have only C.

Anonymous said...

Is there any way the last online quiz can be re-opened? I went to complete it today, as all the pervious quizzes have been due on Sunday, only to find it was actually due yesterday!

nn said...

i was going over a question in one of the exams and it asked what the maximum number of electrons that can have n=2 and ms= -1/2 and the answer was 4 and i wasn't sure why?

Anonymous said...

i was going over a question in one of the midterms and it asked what the maximum number of electron that can have n=2 and ms=-1/2 and the answer was 4 and i wasn't sure why?

Anonymous said...

whats the difference between an amide and an amine

Anonymous said...

Where can I get the solution for Uvic Chem101 exam for Fall 2010

Anonymous said...

Where can I get the solution for Uvic Chem101 exam for Fall 2010

Anonymous said...

On Section 2.5 of the Chemistry Lecture Booklet, it states that Electron affinity is negative for stable anions but the chart under it shows that electron affinity is positive for stable ions (Be, Ne, etc...). Is that a booklet mistake or am i misunderstanding something?

Scott McIndoe said...

Re: max # of electrons - for n = 2, we're talking about the 2s and 2p, a total of 8 electrons. 4 of them are spin up, 4 are spin down (ms = -1/2).

Re: amide/amine - amide functional group is R-CONHR, amine is RNH2 (or R2NH, R3N, etc). The thing to look for is whether N is next to a carbonyl group or not.

Re: solution for final exams - not available online. You could buy them last week from ChemSoc (caveat emptor!), and I also went through the summer 2010 one yesterday at the review session.

Re: Electron affinity - is exothermic when acquiring an electron is favourable (e.g. O, F) but positive (endothermic) when it is not (e.g. N, where you're pairing an electron in an orbital).

Anonymous said...

Were we told that the last chem quiz was due on Saturday Dec 8? I thought it was Sunday!!

Anonymous said...

and by 8th i mean 3rd

Scott McIndoe said...

The deadline was extended 6 days from what I told you it was in class (and what it says on http://web.uvic.ca/~chem101/quizzes.html). The course coordinator sets the quizzes and the dates; I can't help, sorry.

Anonymous said...

Why is Homework Asignment #1 on mastering chem not available?

Anonymous said...

I dont understand how we are just supposed to no the reactions (condensation, additional, etc) for chapter 7. I have read the text book, done the assignments, looked over finals and they are always 10-15 marks on the finals and i can not grasp it! How can I understand them better?

Scott McIndoe said...

Addition reactions: X2 (where X is usually H, Cl, Br, I) added to double and triple bonds. They convert the pi bond(s) into new sigma bonds to X. So H2C=CH2 -> XH2C-CH2X, for example.

Condensation reactions: you learned RCOOH + HOR' -> RCOOR' + H2O (ester from carboxylic acid and alcohol) and RCOOH + H2NR' -> RCONHR' + H2O (amide from carboxylic acid and amine).

Substitution reactions: for aromatics. Addition doesn't happen because the stability gained from delocalization of the pi bonding would be lost, so substitution happens instead. E.g. C6H6 + HNO3 -> C6H5NO2 + H2O (substitution of -H with -NO2).

Combustion: CxHy + O2 -> CO2 + H2O

That's most of what you need to know, and about the best I can do here!

Anonymous said...

Can you explain what lattice Energy is and how we find it?

Anonymous said...

Help! Number 1 from practice quiz in lab manual:
An election is traveling with a velocity of 1.21x10^8m/s. The uncertainty of measuring its velocity is 10m/s. What is the minimum uncertainty of measuring its position (in meters)?

Scott McIndoe said...

Lattice energy is the sum of all the attractive and repulsive electrostatic forces in an ionic lattice. It is a large -ve number that is roughly proportional to the product of the charges on the anion and cation divided by the interatomic distance. So ionic compounds made from small, multiply charged ions have a higher lattic energy than those made from large, singly charged ions.

Scott McIndoe said...

Use the equation (delta x)(delta mv) >= h/4 pi. Use the uncertainty (10) rather than the absolute value for v; rearrange i.e. (delta x) = 10*m*h/4 pi (m is the mass of an electron, from your data sheet).

Anonymous said...

Number 5 Dec 2010 final:
With regards to the ground state of a Rb atom, why would "There are 9 elections with l=1" be correct?

Anonymous said...

The question is as follows:
"An indium (In) atom has 49 electrons. Electrons in which subshell of the ground state In atom experience the lowest effective nuclear charge?

The solutions to the exam from the chem society says the answer is 4d. However, Briggs says it is 5p.

So what the hell is the correct is answer?

Anonymous said...

HellO!

- the electronic configuration for co (3+) ion is [Ar]3d5 4s1 or [Ar]3d6?

- do we need to know the catalysts?

- high IE means it's harder to remove electrons?

- what does higher Zeff mean?

- is l always 0 to n-1 right?

- how do we know if a rxn does not go to completion

Anonymous said...

Hi, I was going through my quiz #8, and found I had gotten half of them wrong. I went back and checked all my answers and found that most of my answers were actually correct. Where do I go to fix this?

Anonymous said...

If one mole of photons has energy of 845KJ, what is the frequency associated with these photons?
- i got the answer to be 1.27e39. I dont understand why it's actually 2.12e15

Anonymous said...

Sn has 50e. electrons in which subshell experience the lowest zeff?

how do you do that question

Anonymous said...

whats the molten form

Anonymous said...

can something be chiral if it has a double bond?

Anonymous said...

Good afternoon Dr.,

When calculating the energy of a band gap, why do we have to times the result of the E=hv equation by 6.023x10^23?

Anonymous said...

would butane have a higher boiling point than 2 methylbutane?

the methylbutane would be more spherical but it has a greater number of electrons...


Also, would we have to recognize polymers (such as nylon) to answer questions like a solid is hard. brittle and have a mp of 790degre. the solid doesnt conduct but it does in molten form...

The answer is KCl, options were nylon, napthalene, quartz, nickel, kcl

Now napthalene, quartz and kcl dont conduct while in solid form but what about nylon? quartz have an extremly high mp so that gets ruled out, napthalene is carbons in aromatic fashion, so thats gone...so it comes down to nylon and kcl..

Scott McIndoe said...

Re: #5 - it's incorrect, so D is the right answer for that question.

Re: 4d vs 5p - Briggs is correct. Basically, the most shielded electrons are those added last when you fill up your configuration according to the PT.

Re: hello! - transition metal IONS never have s electrons, so it's [Ar]3d6; no; yes; higher Zeff means a higher attraction between electrons and nucleus (usually due to the fact that electrons in the same shell shield each other poorly); don't understand the question; by measuring the extent of reaction experimentally?

Scott McIndoe said...

Re: quiz #8 - talk to the course coordinator, he sets and manages the quizzes.

Re: Sn - basically, the most shielded electrons are those added last when you fill up your configuration according to the PT. So for Sn, 5p.

Re: molten = liquid

Re: chiral - no, unless is has a tetrahedral C atom somewhere in the molecule with 4 different groups on it.

Scott McIndoe said...

Re: band gap - please give me more details.

Re: methylbutane would be higher, no. of electrons trumps shape.

If nylon DID conduct, it wouldn't matter if it was solid or in solution, so the answer is KCl.

Anonymous said...

The shape of TeF4 would be a see saw shape correct? the answer key says trig pyramidal( only possible for shapes derived from tetrahedral)

Scott McIndoe said...

TeF4 is see-saw shaped, yes.

Anonymous said...

is there some sort of special stability that exists for atoms that have half filled shells rather than full?

such as Cl?

Scott McIndoe said...

Do you mean Cr? = [Ar] 4s1 3d5?

Anonymous said...

30. Considering likely intermolecular forces, which of the following should have the lowest boiling point?
A. CH3-O-CH3
B. CH3CH2OH
C. CH3CH2CH3
D. CH3CH2SH
E. CH3CH2CH2CH2CH3

The answer to the questions is B but I'm wondering why it wouldn't be D.

Scott McIndoe said...

The answer should actually be C: only London dispersion forces, but less electrons than E. The answer is exactly wrong.

Anonymous said...

Yes like Cr...but does this only apply for half filled d-orbitals, not p-orbitals or s-orbitals?

Anonymous said...

could you explain this question ?

The group where all members have positive electron affinities is

Li, Na
Li, Be, B
N, O, F
F, Cl, Br
N, He, Ne

Scott McIndoe said...

Re: Cr; yes, only for d orbitals.

Re: group with positive EA. Poor choice of wording with "group". "Selection" or something would have been better. Anyway, the answer is N, He, Ne. He and Ne because the extra electron would have to go in a shell with a hgigher principal quantum number, which is energetically unfavourable. N because the electron goes into an orbital that is already occupied, and the e-e repulsion in a small orbital is high (which is why P has a small negative EA - the orbitals are bigger and hence e-e repulsion is less). There is also e-e repulsion when adding e to O or F, but the high Zeff makes up for it.

Anonymous said...

Thanks a lot for taking all that time and effort to answer all the questions. I really appreciate it.

Anonymous said...

what kind of hybridization would occur in ClO2? the answer key for a prac final says sp3d2....that seems very wrong...

Scott McIndoe said...

Re: thanks - you're welcome, of course.

Re: ClO2 - it's an odd-electron species, and you'd write it ::O=Cl:.=O::, so 4 electron domains on Cl (2 double bonds, one non-bonding pair, one non-bonding single electron). So it would be based on a tetrahedron (sp3) and hence be bent.

Anonymous said...

Alright!

Thank you so much for your help this semester sir!!!!

I think I can definitely get 90+ on this final because of this medium and your help.

I don't believe you are teaching Chem102 next semester?

Scott McIndoe said...

You're welcome - and good luck on the final.
No 102 for me - the instructors will be Sandy Briggs, Hugh Cartwright and Rob Lipson.

Anonymous said...

Just wanted to say thanks for being a great prof!

Scott McIndoe said...

Thank you!

Anonymous said...

for one of the questions on the final...what would be the product with benzene attached with CH2CHOH is reacted with an oxidizing agent....?

Scott McIndoe said...

The aldehyde C6H5CH2CHO is the least oxidized product, but the carboxylic acid (or even CO2 + H2O!) would have been acceptable.

Anonymous said...

Thanks for being a great professor! You're definitely my favourite prof. I enjoyed your lecture and you made everything very clear

Scott McIndoe said...

Thanks!

Anonymous said...

First of all best professor Ive had so far, and secondly whats next in the horizon for you? teaching anymore lectures next semester?

Scott McIndoe said...

Thanks. I'm not teaching in the Spring or summer terms, so you're not likely to see me again until 4th year... (unless you're looking for some chemistry research experience of course!).

Anonymous said...

I was wondering when and where we can see our grades once the finals are marked? Thanks for being a great prof this semester... it made chemistry A LOT more enjoyable for me!

Impatient Student said...

Hey! Thanks for the awesome semester. you are by far one of my favourite teachers.
Do you know when we will know the results of the final and our final grade in the course?

Scott McIndoe said...

Thanks for the positive feedback, much appreciated. The exam is mosted marked now, but it will take some time to assemble all the bits and pieces. Probably about a week from now you'll know; I'll post here when the grades are out.

Anonymous said...

Agreed, you were a great prof, thanks you

Anonymous said...

Thank you for being the BEST PROF!
You are simply an amazing instructor! HATS OFF!!!

Will we get our exams back today by any chance?

Scott McIndoe said...

Thanks all. Your exams are marked and all the grades for all the various components are in the hands of the course coordinator. However, assembling all this information and ensuring it is error-free is no small task, so it may be a few more days yet before your grade appears on your "My Page". I will announce on the blog when the course coordinator has submitted the grades - it may take up to a day after that to filter through to you.

Anonymous said...

Could we know the class average for the final? Thank you!

Anonymous said...

Yes, will we get to know our final exam mark as well as our overall grade?

Anonymous said...

The final marks have been posted, but is there anywhere that the grade breakdown will be available?

Scott McIndoe said...

Yes - email me and request it.