VCE Chemistry Question Thread

[jyce]

Hey guys, I know I haven't been on here lately and this message is probably a bit late - but I just wanted to say best of luck to all you ANers sitting the Chem exam tomorrow!! I've seen you guys asking lots of thoughtful questions and helping one another on here throughout this whole year. Have faith that you know your shit and do the best you can tomorrow 

Which part of the electromagnetic spectrum does AAS use?

Visible light

[Swagadaktal]

TLC: Usually dyes or amino acids - soluble compounds in solvent, can detect small amounts
HPLC: big masses, must be soluble in eluent  (200g+) - what compounds generally
GC: small masses, must be volatile (can be vaporised)

anything else i should add?
And AAS can only be qualitative right?

[julijulib]

Hey everyone,
Just seen some notes floating around around multiplying something to find the number of splits for a 1HMR peak set, unlike the general (#of H neighbours + 1) rule to find the number of splits. Is this something we need to know and if so could someone please explain it?
Thanks a lot!

[jyce]

Hey everyone,
Just seen some notes floating around around multiplying something to find the number of splits for a 1HMR peak set, unlike the general (#of H neighbours + 1) rule to find the number of splits. Is this something we need to know and if so could someone please explain it?
Thanks a lot!

Nope, stick to the n + 1 rule.

I'd highly recommended only reading your own notes at this stage, so as to not freak yourself out if you read something you're unfamiliar with.

[jazzaa36]

Can some please quickly explain the % DNA questions, ive been avoiding DNA for a while, now im regretting it 

[HopefulLawStudent]

Do fuel cells generate AC or DC current? It's DC right? If it's DC could that be counted as a disadvantage? Because most appliances require AC?

[Sine]

Do fuel cells generate AC or DC current? It's DC right? If it's DC could that be counted as a disadvantage? Because most appliances require AC?

Disadvantage - produces DC current hence requires it to be converted to AC current to be utilised as you say for most appliances.

[Swagadaktal]

Do fuel cells generate AC or DC current? It's DC right? If it's DC could that be counted as a disadvantage? Because most appliances require AC?

brah this aint physics get yo dc ac outta here

but seriously i think you're analysing way too indepth (outside scope of SD) so that could come to your detriment

[julijulib]

Also, why does the electrolyte in electroplating have to contain cations of the metal being plated?
Is it just to ensure the concentration of ions stays constant to ensure an even coating? I really have no clue
Thanks!

[HopefulLawStudent]

Cool cheers Swag. It's in my notes and I got soooo confused. Gonna just keep clear of it then.

EDIT: Thanks Sine!

[HopefulLawStudent]

TLC: Usually dyes or amino acids - soluble compounds in solvent, can detect small amounts
HPLC: big masses, must be soluble in eluent  (200g+) - what compounds generally
GC: small masses, must be volatile (can be vaporised)

anything else i should add?
And AAS can only be qualitative right?

AAS is quantitative too isn't  it? You can calc concentration from it...

[Swagadaktal]

AAS is quantitative too isn't  it? You can calc concentration from it...

Yeah Im a silly goose

[bedigursimran]

Hey guys. I just need a quick refresher on the DNA's primary, secondary and tertiary structure. I know secondary has hydrogen bonds and tertiary has dispersion forces. Please help. It doesn't have to be long, just a quick point about each in terms of being on the exam would be immensely appreciated!

[lzxnl]

Also, why does the electrolyte in electroplating have to contain cations of the metal being plated?
Is it just to ensure the concentration of ions stays constant to ensure an even coating? I really have no clue
Thanks!

Well if you have another kind of ion, you might plate that instead. Your metal cations are what's in contact with the cathode. The plating process itself is a reduction of the metal ions to form solid metal. The ions are the reactants.

Hey guys. I just need a quick refresher on the DNA's primary, secondary and tertiary structure. I know secondary has hydrogen bonds and tertiary has dispersion forces. Please help. It doesn't have to be long, just a quick point about each in terms of being on the exam would be immensely appreciated!

Primary: covalent bonds between atoms, won't break with heat or pH
Secondary: hydrogen bonds between C=O and NH; these can break with heat, responsible for helical structure of DNA
Tertiary: anything else, like electrostatic between protonated amines/deprotonated carboxylate groups, hydrophobic interactions, dipole-dipole interactions etc. These are broken pretty easily

[Sine]

Hey guys. I just need a quick refresher on the DNA's primary, secondary and tertiary structure. I know secondary has hydrogen bonds and tertiary has dispersion forces. Please help. It doesn't have to be long, just a quick point about each in terms of being on the exam would be immensely appreciated!

primary - number sequence and type of nitrogenous bases along the sugar phosphate backbone which is held together by phosphodiester linkages(covalent bonds).
secondary - The helical structure of double stranded DNA held together by hydrogen bonding between complementary bases

not on SD - although taught
Tertiary - the way in which DNA wraps it's self around histone proteins via ionic bonds.

Its chemistry so the most important points are the types of bonds.

beaten by |zxn|