1. CHEMISTRY 3.5 ANSWERS
WORKSHEET TWO ORGANIC Isomerism
1. Isomers have the same molecular formula but different structural formula.
2. pentane CH3CH2CH2CH2CH3 2-methylbutane CH3CH(CH3)CH2CH3
2,2-dimethylpropane (dimethylpropane) CH3 C(CH3)2CH3
3. but-1-ene CH2CHCH2CH3 but-2-ene CH3CHCHCH3
2-methylpropene CH2C(CH3)CH3
4. propanal CH3CH2CHO propanone CH3COCH3
5. (a) The molecule will have a chiral carbon atom, ie a carbon atom with four
different groups on it.
(b) Two enantiomers have identical chemical properties, but in biochemical
systems they behave differently. They also have the same physical
properties except for their effect on plane-polarised light. One
enantiomer will rotate the plane of polarisation clockwise and the other
anticlockwise.
(c) Many biological molecules such as amino acids are optically active.
Often only one of the isomers is able to function properly in living
things.
6. (a) (b) CH2 CH3
CH3CH2 CH3CH2
H2C CH CH CH3
C C
CH3 CH3
H Cl
Cl H
7. (a) NH2CH2CH2CH2CH(CH3)COOH
(b) CH3CHClCH2CHClCH2CH3
(c) CH3CHO
(d) CH3CH2CHBrCH3
(e) (CH3)2CHCH(CH3)COOH
(f) Any of the above arranged as in answer 6(a) above.