SUGGESTED ANSWERS!!!

[Sashissokool]

Hey guys, this is probably gonna be a weird question...but with Q7 of MC, the one about enzymes, did you not find it a bit ambiguous?

Because one of the options talked about 'the substrate forms bonds with the active site', but it didn't specify what bonds...like, it could have been permanent bonds, or temporary bonds, or anything!

And if it were PERMANENT bonds, then that statement would have been wrong...meaning option A would have been correct. The reason its concerning me more is because in a previous VCAA exam (i think 2009), in a MC question similar to these, they talked about enzymes specifically forming TEMPORARY ion-dipole bonds, or some shiz like that...

I'm probably reading too much into it, but yah

[charmanderp]

Bonds are bonds are bonds are bonds are bonds are bonds are bonds are bonds are bonds (not the underwear brand btw)! The fact that it forms any bonds at all probably validates that statement. I think the trick intended there was for students to think that the substrate fit into the enzyme simply because its shape was complementary to the active site, where as it was this and inter-molecular bonding.

[supermanflyaway]

What do you guys think an A+ will be?

[MWPlatt]

Question 1b SA

Anyone else noticed the C=C instead of a C=O on the bottom third of the triglyceride? XD

[sin0001]

yea, the examiners found out halfway through, didn't even notice it lol

[12of2012]

with 5iii) wat i did was write down 3 and 2 assuming two carbon atom on each side 3*2=6     and n+1   therefore 6+1 =7 so septet would that be counted as wrong ?? oh god!!

[monika.s]

For the CH3CH2OH(aq) + CH3CH2COOH(aq) -----> CH3CH2COOCH2CH3(aq) + H2O(l):

Will I lose a mark for that not being all (l). Because I thought that if water was produced, that means that they would be aqueous? I know I'm wrong, but how am I wrong?

[johnny77]

why wasnt it 360mg ? 

[vnguyenprochemist]

why wasnt it 360mg ? 

The concentration was 360mg/L, however the question said that each tablet was dissolved in 100mL of water. Therefore it was 360X0.100L, which equals 36mg.

[thushan]

For the CH3CH2OH(aq) + CH3CH2COOH(aq) -----> CH3CH2COOCH2CH3(aq) + H2O(l):

Will I lose a mark for that not being all (l). Because I thought that if water was produced, that means that they would be aqueous? I know I'm wrong, but how am I wrong?

Oh, because not enough water is produced to form a proper aqueous solution - you'd need a lot of water relative to other compounds to form a real aqueous solution. Anyhow, the water produced is just absorbed by the H2SO4 catalyst (which is an awesome dehydrating agent).

[Oakleaf]

I put option A for question 5 because technically, it is the hydrogen bonding between -NH and -C=O, not -CO. Is this ambiguity or my not knowing how to read questions?

[thushan]

I put option A for question 5 because technically, it is the hydrogen bonding between -NH and -C=O, not -CO. Is this ambiguity or my not knowing how to read questions?

CO often implies C=O, like for instance HCOOH --> the CO refers to C=O.

[Louise clover]

how do we get consequencial marks in a chemistry exam, because i put down propanol instead of propan-1-ol, and i did the same thing in the flowchart that describes how we could extract pure propyl propanoate, but when i write down the semistructural formulae, i put down propan-1-ol. would i loose alot of marks for this?

[thushan]

how do we get consequencial marks in a chemistry exam, because i put down propanol instead of propan-1-ol, and i did the same thing in the flowchart that describes how we could extract pure propyl propanoate, but when i write down the semistructural formulae, i put down propan-1-ol. would i loose alot of marks for this?

Probs lose only 1 mark for that.

[melissaparks]

Quick question

I've made the dumbest mistake and read that graph wrong and i got 38mg instead of 36 but i showed all my working out so the examiner will realise it was because i read it wrong...
what do you reckon will happen? Will i drop 1 mark or 1/2 mark??? or 2 marks?

Thanks