OCR F324-June 2013 Chemistry

Hi how are you


Benzene, is a cyclic hydrocarbon and contains only carbon and hydrogen only. It is a trigonal planar (molecule/structure) and bond angle around each carbon atom is 120. Benzene has 4 outer shells of electrons, three of these electrons are shared between a carbon atom and one of the hydrogen atom, this called sigma bond and is sited above and below the plane of the carbon (C-C) bond. The 4th outer shell of electron is the 2p orbital in which the p orbital overlaps and creates a region of high electron density. The benzene is delocalised as the electrons are shared between the 6 carbon atoms , through out the whole structure. Also, in benzene the c-c bond length is the same.

you got full marks,

what causes optical isomerism? [2]

got a feeling its going to be a killer paper :/

Do you mean that it will be hard?

ok thanks!


If a chiral carbon is present in which the carbon is attached to 4 different atoms/groups of atoms and also that the 2 images are non-superimposable images of each other.

excellent answer, worth 3, infact,

my turn!

after the nice jan paper, yeah :/

Thanks


Stage the reagents and conditions needed for going from 3-chloropropan-1-ol to 3-aminopropan-1-ol (3)

( excess) NH3, ethanol? is it gently heated or something?

got a feeling its going to be a killer paper :/

yes well done!


Give 2 uses of polyesters (2)

clothes, plastics

1) what is the structural formula of a lactic acid monomer

clothes is correct, not sure about plastics, I would put carpets.


2-hydroxpropanoic acid

HOCH(CH3)COOH

conditions/reagents for hydrolysis of
1)polypeptides
2) polyesters
3)polyamides

hydrolysis of polypeptides, conditions , add HCL(aq) and heat under reflux for24 hours 6 mol dm-3, also alternatively under alkaline conditions usually with NaOH(aq)


Hydrolysis of polyesters, addition of h2o/H+ , heat under reflux , alkaline conditions


hydrolysis of polyamides, addition of aqueous HCL/ H2O and heat under reflux or again under alkaline conditions

correct, all of them can be done in acid or alkali conditions, water needs to be present always, water solvent

thanks

Define:zwitterion


Define:isoelectric point

dipolar ionic form of an alpha amino acid, contains both positive and negative charges which cancel out leaving no overall charge,

the pH level where the zwitterion exists

yep, very nice!


my turn

whats the name of a fatty acid which is represented as 6:1(3) ?