VCE Chemistry Question Thread

[lzxnl]

Okay phew. Thanks )



Is the reaction between salicylic acid and ethanoic anhydride a substiution reaction?

Yes, it's a substitution. Esterification reactions are a special class of substitution in which the alcohol reacting with the acid substitutes for the OH group. The alcohol's original OH hydrogen is then transferred to the leaving OH group, giving the familiar condensation reaction.

[psyxwar]

Do dispersion forces exist between the compound and the mobile phase in gas chromatography?

[vox nihili]

Do dispersion forces exist between the compound and the mobile phase in gas chromatography?

If two things are coming into contact, odds on there are Van der Waals forces.

[Rishi97]

Do we need to know the replication of DNA for chem? Its in ch 13 pg 209

[psyxwar]

If two things are coming into contact, odds on there are Van der Waals forces.

Yeah thats what I thought but the AN study guide for chem says they dont exist

[thushan]

Not in gas chromatography. The only reason that the sample is being swept along the column is because the mobile gas molecules are literally colliding with and knocking the sample molecules along the column. Theoretically, there would be van der Waals forces when the particles are close, but remember that the molecules would be passing one another at such high speed - we're talking gas here - that they would only be close to one another for a  fleeting amount of time.

[soNasty]

Can someone tell me how CCl3CH2CCl3 is non polar, it looks like the molecule is pretty symmetrical

[psyxwar]

Not in gas chromatography. The only reason that the sample is being swept along the column is because the mobile gas molecules are literally colliding with and knocking the sample molecules along the column. Theoretically, there would be van der Waals forces when the particles are close, but remember that the molecules would be passing one another at such high speed - we're talking gas here - that they would only be close to one another for a  fleeting amount of time.

Ah fair enough, thanks

[Rishi97]

Can someone tell me how CCl3CH2CCl3 is non polar, it looks like the molecule is pretty symmetrical

If a molecule is symmetrical, it's non polar. I think you got a bit confused...
Remember this acronym SNAP
Symmetrical Non-polar Asymetrical Polar

[soNasty]

If a molecule is symmetrical, it's non polar. I think you got a bit confused...
Remember this acronym SNAP
Symmetrical Non-polar Asymetrical Polar

Oh wow haha thanks :p

[Rishi97]

Can someone please help me name the following compound?
Sorry for the horrible drawing

[drake]

1-amino-3-methylbutane

[Rishi97]

1-amino-3-methylbutane

So does the amine group have to be on the smallest number of carbon or the methyl group?

[saba.ay]

So does the amine group have to be on the smallest number of carbon or the methyl group?

The amine has to be on the smallest Carbon. When naming, you work your way down the following list, giving the top one the smallest Carbon number:

• COOH group
• OH group
• NH2 group
• C=C double bond
• halo substituents (Cl, F, Br, I)
• alkyl groups (methyl, ethyl, etc)

[Rishi97]

The amine has to be on the smallest Carbon. When naming, you work your way down the following list, giving the top one the smallest Carbon number:

• COOH group
• OH group
• NH2 group
• C=C double bond
• halo substituents (Cl, F, Br, I)
• alkyl groups (methyl, ethyl, etc)

omg that's such a great tool. Thanks so much