Chemistry unit 4 AQA

What's likely to come up on chromatography?

I think gal liquid chromatography will probably come up,

can someone explain optical isomers, i hate it :/

my teacher reckons this exam is gonna be really hard because apparantly CHEM1 was really tough.

Optical Isomers have a chiral carbon, so each chain coming off the C atom is different.

also they are mirror images so they can't be superimposed (basically a good example is your hands... put them on top of each other any they are not the same, they are mirror images...)

So in the exam they will probs ask you what kind of isomerism a molecule is... Just search for the chiral carbon and that's pretty much it...

Need anymore help?

Thankyouu
can you explain what racemic means? thanks

There is an equal amount of each optical isomer produced (50:50)this mixture is called a racemic mixture or racemate
Hope dat helps hehe

quick prayer to the chem gods should sort that **** out :P

my teacher reckons this exam is gonna be really hard because apparantly chem1 was really tough.

chem 1 was horrible.

Thanks

I resat chem 2 yesterday and it was a quite an easy paper
wishing chem 4 will be the same

you can determine which enantiomer (optical isomer) is present in a solution by passing the solution through a plane of polarised light. One enantiomer will rotate the plane anti-clockwise, the other will rotate it clockwise. A racemate/ racemic mixture will not do this so it is optically inactive

the importance of finding the optical isomer is mainly for medicine, because one can have the desired effect, one can have side effects.

however racemates are favored in the industrial process as it is very expensive to separate the mixture to give the 2 enantiomers

chem 2 was good! but i dont want to tempt fate ><

yup what do you find the hardest?

pH and buffers are like the only parts of chem 4 I'm happy with, all the maths bits too, organic chem is a killer

i find ph and buffers and all the maths part really easy, don`t like organic :/