Chem Questions

[horizon]

A stomach enzyme is heated and denatured.  The bonds which hold an enzyme together include:
I dispersion forces
II dipole dipole bonds
III hydrogen bonds
IV covalent bonds
When the enzyme is heated from 25 degrees C to 90 degrees C, bonds affected include:
A. I and IV
B. I and III
C. I, II, III and IV
D. II and III only.

Answer is B, but I don't see why...

[Somye]

MHS trial?

... really crap question, I asked Sarbinowski about it, his answer was that I,II and III are affected, but because D, the only other possible correct answer has 'only', it must be B

[pi]

Yep, I to IV are ordered from weakest to strongest. Under that temperature range, I, II and II would all be effected. B is the best answer as it has options that are ALL effected although it doesn't have all the ones that are effected in TOTAL.

[charmanderp]

Whenever III is affected that should mean II is affected too, seeing as hydrogen bonds are just a more focused form of dipole-dipole interactions.

VCAA would probably avoid those kinds of questions, as they're a bit too ambiguous. No offence to the above but I didn't really like the MHS exams :p

[Somye]

hahaha yeah, they contain a couple of dodgy questions, but overall, they're not a bad confidence booster :p

[horizon]

wait, so are disulfide bridges broken in the tertiary structure during the denaturation of a protein or not?

[thushan]

wait, so are disulfide bridges broken in the tertiary structure during the denaturation of a protein or not?

nah

[pi]

wait, so are disulfide bridges broken in the tertiary structure during the denaturation of a protein or not?

Depends on the denaturation, if you heat it to like 300 degrees C, then probably. If only to like 100 degrees C, then probably not.

[horizon]

In the priority for naming, do haloalkanes come before alkyl groups or the other way around?
For example: Would it be 3-chloro-6-methylheptane or 5-chloro-2-methylheptane?

[mihir94]

3-chloro-6-methylheptane. Alkyl groups have the least priority when numbering.

[aznxD]

Don't alkyl groups have equal priority to halogens?
http://butane.chem.uiuc.edu/cyerkes/Chem104A_BFA05/Genchemref/nomenclature_rules.html

[milaseret]

I'm still confused about the terms:

reduces, oxidises, reductant, oxidant, reduction and oxidation!

Can someone please piece these together?

[AllAboutTheLGs]

In the priority for naming, do haloalkanes come before alkyl groups or the other way around?
For example: Would it be 3-chloro-6-methylheptane or 5-chloro-2-methylheptane?

In the VCAA assessors report, they were both accepted. I personally use 5-chloro-2methylheptane 5+2 < 3+6

[AllAboutTheLGs]

I'm still confused about the terms:

reduces, oxidises, reductant, oxidant, reduction and oxidation!

Can someone please piece these together?

Reduction is gain of electrons. The oxidant is reduced, gaining electrons.
Oxidation is loss of electrons. The reductant is oxidised, losing electrons.

[milaseret]

Reduction is gain of electrons. The oxidant is reduced, gaining electrons.
Oxidation is loss of electrons. The reductant is oxidised, losing electrons.

Thanks so much!