VCE Chemistry Question Thread

[Elizawei]

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

I would have assumed it to be an addition reaction, and X is propene.
would be C3H6 + Br2 --> BrCH2BrCHCH3

two mol of propene also forms 6 mols of CO2.
2C3H6 + 9O2 -> 6CO2 + 6H2O

[jyce]

I would have assumed it to be an addition reaction, and X is propene.
would be C3H6 + Br2 --> BrCH2BrCHCH3

two mol of propene also forms 6 mols of CO2.
2C3H6 + 9O2 -> 6CO2 + 6H2O

Yeah, I did say that X *could* be propanol. The question doesn't provide enough information to know for sure.

EDIT: Come to think of it, though, propene does seem like the more simple solution.

Would be nice to know how many moles of water are produced 

[HopefulLawStudent]

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?

It's an error in the question.

[EXO96]

Hey guys,

In TLC, is the reason for putting a cap on the chamber to increase the pressure for capillary action OR to saturate the atmosphere with solvent vapor?

Is it both?

Thanks 

[jazzaa36]

MC QUESTION:
how many structural isomers are possible for 1,1-dibromobutane?
A.4
B.5
C.6
D.7

[Elizawei]

MC QUESTION:
how many structural isomers are possible for 1,1-dibromobutane?
A.4
B.5
C.6
D.7

I thought there were 9 including 1,1-dibromobutane

[jazzaa36]

so i guess ill just put down 7   

[Elizawei]

so i guess ill just put down 7   

Yeah haha, where's this question from? Some commercial papers are quite dodgy

[jyce]

MC QUESTION:
how many structural isomers are possible for 1,1-dibromobutane?
A.4
B.5
C.6
D.7

Yeah, there are 9.

1. 1,1-dibromobutane
2. 1,2-dibromobutane
3. 2,2-dibromobutane
4. 1,3-dibromobutane
5. 2,3-dibromobutane
6. 1,4-dibromobutane
7. 1,1-dibromomethylpropane
8. 1,2-dibromomethylpropane
9. 1,3-dibromomethylpropane

[jazzaa36]

what "simple" method to distinguish between a polyunsaturated fat and an saturated one?
Would it be test in bromo water OR test melting points??? 

[jyce]

what "simple" method to distinguish between a polyunsaturated fat and an saturated one?
Would it be test in bromo water OR test melting points??? 

The bromine test.
- An unsaturated fat will decolourise a bromine solution due to bromine being added across the C=C bonds in the fat.
- A saturated fat does not have C=C bonds and so no addition reaction occurs and the bromine solution stays its reddish-brown colour.

[jazzaa36]

What is an monomer of this polymer?
 
  CH3            H                    H                    H                CH3               C

---C------------C----------------C----------------C-------------C---------------C------

   H                H                   H                     CH3            H                  H

THANKS IN ADVANCE 

[jyce]

What is an monomer of this polymer?
 
  CH3            H                    H                    H                CH3               C

---C------------C----------------C----------------C-------------C---------------C------

   H                H                   H                     CH3            H                  H

THANKS IN ADVANCE 

Looks to be propene.

EDIT: Is that carbon atom in the top right supposed to be a hydrogen atom?

[jazzaa36]

Hahah yeah it's ment to be a H atom, could please explain as why it is propene  thanks heaps btw

[jyce]

Hahah yeah it's ment to be a H atom, could please explain as why it is propene  thanks heaps btw

You find the repeating unit. In this case, it's CH₃CHCH₂. Then it's simply a matter of naming the monomer.