VCE Chemistry Question Thread

[Adequace]

Possible dumb question but are we expected to memorise alkyl groups? (pls no downvote)

[Syndicate]

Possible dumb question but are we expected to memorise alkyl groups? (pls no downvote)

Yes. For VCE unit 1, you are only expected to know groups upto butyl.

[keltingmeith]

Possible dumb question but are we expected to memorise alkyl groups? (pls no downvote)

Certainly - but they don't need to be difficult! It's basically the alkane chain but one less proton (which is bonded to the larger chain)

For example:

Methyl = CH3 (Methane=CH4)
Ethyl = C2H5 (Ethane = C2H6)
Butyl = C4H9 (Butane = C4H10)
Dodecyl = C12H25 (Dodecane = C12H26)

Also, I wouldn't expect to see more than a propyl, so I wouldn't worry too much past them, either!

[JellyBeanz]

Possible dumb question but are we expected to memorise alkyl groups? (pls no downvote)

Haha, relax, no question is a dumb question here.

Don't need to say that XD

[Adequace]

Ah, okay. Thanks everyone 

[CarrymetoUni]

I just had the Chem exam and there was a question asking why can't non polar molecules dissolve in water?
I said that it was because the non polar molecules were hydrophobic, which prevented them from dissolving in water.
I just wanted to know if this was the correct response because my friends are telling me that I shouldn't have used a biology term in the question since we haven't been told anything about terms such as hydrophobic and hydrophilic in Chem.

[jyce]

I just had the Chem exam and there was a question asking why can't non polar molecules dissolve in water?
I said that it was because the non polar molecules were hydrophobic, which prevented them from dissolving in water.
I just wanted to know if this was the correct response because my friends are telling me that I shouldn't have used a biology term in the question since we haven't been told anything about terms such as hydrophobic and hydrophilic in Chem.

Using the terms "hydrophobic" and "hydrophilic" in Chemistry is fine. However, in my opinion, you're response that non-polar molecules cannot dissolve in water because they are hydrophobic is not specific enough. What does hydrophobic actually mean? I would have written something like: "Non-polar molecules cannot dissolve in water as they can only form weaker intermolecular forces with water molecules (e.g. dispersion forces) than what water molecules already experience among themselves (hydrogen bonds)."

[HasibA]

hey guys- what's one way we can make the production of aspirin more 'greener'!? getting conflicting info that beyond VCE from google- and i really only need a brief response for my chem sac soon! thanks guys- really appreciate it

[jyce]

hey guys- what's one way we can make the production of aspirin more 'greener'!? getting conflicting info that beyond VCE from google- and i really only need a brief response for my chem sac soon! thanks guys- really appreciate it

e.g. recycling the ethanoic acid produced as a by-product

[jazzaa36]

X burn excess oxygen. Two mole of compound form six mole of carbon dioxide, What is x???
HELPPP !!

[jyce]

X burn excess oxygen. Two mole of compound form six mole of carbon dioxide, What is x???
HELPPP !!

Could be propanol.

2C₃H₈O + 9O₂ -> 6CO₂ + 8H₂O

[jazzaa36]

much love man

[jazzaa36]

now if X reacts with bromine it will be a substitution reaction right ?
CH3CH2CH3O+Br2=CH3CH2CH2BR??
or is CH3CH2CH3O+Br and not Br2??

[NerdyPi]

Hi guys, so I need some clarification with marking a practice exam (Unit 3 STAV 2016):

For question 2, e) it asks for you to suggest 4 ways to improve a gravimetric analysis, and states that "discretion" can be used to determine possibilities other than those listed in answers. For the two points which I'm unsure about, I had
- Redo experiment to ensure consistent results are obtained
- Check other ingredients in fertilizer, to ensure there won't be other reactions occurring that will affect results (E.g other solids forming)

Would there 2 answers be acceptable?

Also, for question 3, they state "at standard temperature and pressure", but for the N = V/Vm equation, they have taken Vm as 24.5 L/mol, when it says on data booklet that at STP, Vm = 22.4 L/mol???
Is this an error, or am I missing something?

Thanks for the help

[jyce]

Hi guys, so I need some clarification with marking a practice exam (Unit 3 STAV 2016):

For question 2, e) it asks for you to suggest 4 ways to improve a gravimetric analysis, and states that "discretion" can be used to determine possibilities other than those listed in answers. For the two points which I'm unsure about, I had
- Redo experiment to ensure consistent results are obtained
- Check other ingredients in fertilizer, to ensure there won't be other reactions occurring that will affect results (E.g other solids forming)

Would there 2 answers be acceptable?

Also, for question 3, they state "at standard temperature and pressure", but for the N = V/Vm equation, they have taken Vm as 24.5 L/mol, when it says on data booklet that at STP, Vm = 22.4 L/mol???
Is this an error, or am I missing something?

Thanks for the help

All of what you've said seems legitimate to me.