2009 Chemistry Unit 3 Exam Questions and Suggested Solutions

[TrueTears]

That makes me feel better about the ENTER I will need.
Definitely focusing more on English from now on, then.

There's no doubt if you want a good ENTER you must have good English SS. :\

[simpak]

Oh I know that, I was planning to work hard enough to get above 40
But I'm just saying I will pay it a little more attention now, I tend to let it slip a little bit because you can bullshit your way through it more than you can other subjects when you have a lot of assessments on.

[hyperblade01]

Just a little something

Short Answer 9c)

5-bromouracil. Does the uracil in the name help with identifying it as thymine? Because when I saw it that's the first thing that popped into my mind :p


Edit: Jenny i know you're reading this :p

[TrueTears]

Just a little something

Short Answer 9c)

5-bromouracil. Does the uracil in the name help with identifying it as thymine? Because when I saw it that's the first thing that popped into my mind :p


Edit: Jenny i know you're reading this :p

Uracil replaces Thymine in RNA.

[justin]

Why was question 12 b) and not c)?  Is it because you can't add elements in the middle section of a hydrocarbon?

[hyperblade01]

Exactly, so just curious if that association is just a coincidence or not

Bio ftw



Edit:

Why was question 12 b) and not c)?  Is it because you can't add elements in the middle section of a hydrocarbon?

The carbon in the middle is already bonded to 4 other carbons? Is that where you're talking bout?

[simpak]

I don't entirely understand why it wasn't c, either.

[ming_mong]

this exam doesn't look too bad. most students should have found it quite accessible.

Accessible, yes. But to finish with confidence, hell no.

if you had practiced enough, there should not have been any retarding force to prevent you from completing the exam with great prose.

[simpak]

this exam doesn't look too bad. most students should have found it quite accessible.

Accessible, yes. But to finish with confidence, hell no.

if you had practiced enough, there should not have been any retarding force to prevent you from completing the exam with great prose.

Not tru fax!
I practiced more than I have ever practiced for anything in my life >.<

[hyperblade01]

I don't entirely understand why it wasn't c, either.

The three methyl groups are one environment, the CH2 is another and the CH3 on the right is the third

[simpak]

I thought there were four different places because one is closer to the carbon with the whole dimethyl part while the other is further away.
It's probably because I didn't draw it out properly due to timing and I usually get confused by semistructural formula.

[homghomg1]

Hmm i just realised for Aspiring short answer question I rounder off too early. Got 0.016 as number of mol.
this resulted in a 78.1% yield as opposed to 78.4%
it was a 4 part question, each worth 1 mark
do you think they will deduct marks for incorrect number of significant figures? If so, how many? Are there half marks in chem?

[hyperblade01]

Just realised maybe environment isnt the right word, too much NMR in my mind lol

But yea, the 3 methyl groups , whichever one you place the Cl on the molecule is gonna be named the same

[TrueTears]

Hmm i just realised for Aspiring short answer question I rounder off too early. Got 0.016 as number of mol.
this resulted in a 78.1% yield as opposed to 78.4%
it was a 4 part question, each worth 1 mark
do you think they will deduct marks for incorrect number of significant figures? If so, how many? Are there half marks in chem?

Yes they do deduct marks for incorrect use of sig figs. 1 mark off the whole exam.

[simpak]

Just realised maybe environment isnt the right word, too much NMR in my mind lol

But yea, the 3 methyl groups , whichever one you place the Cl on the molecule is gonna be named the same

But it shouldn't, should it?
If you put the chlorine on the first carbon, then it will be 1-choloro 2-dimethyl butane.
But if you put it on the 'last' carbon, then it will be 1-chloro 3-dimethyl butane?
If you put it on the carbon slotted in the middle, then it would be 2-chloro 3-methyl butane?
Or can you not put the chlorine on the methyl groups?

Argh I am probably missing something entirely.  I never do too well with those sorts of questions.