4NA - Organic chemistry

Question 1

which homologous series does the C=C functional group belong to

Answer 1

alkene

Question 2

do alkanes have a functional group

Answer 2

no

Question 3

what are hydrocarbons?

Answer 3

organic compounds that contain hydrogen and carbon ONLY

Question 4

what are the common characteristics among members of a homologous series

Answer 4

same functional group
similar chemical properties
gradual change in physical properties from one member to the next
differ from one member to the next by a CH2 unit
share the same general formula

Question 5

how many carbon atoms does an organic compound have if its name begins with the prefix ‘prop-‘

Answer 5

3

Question 6

how many carbon atoms does an organic compound have if its name begins with the prefix ‘meth-‘

Answer 6

1

Question 7

how many carbon atoms does an organic compound have if its name begins with the prefix ‘eth-‘

Answer 7

2

Question 8

what method/technique is used to separate the fractions of petroleum

Answer 8

fractional distillation

Question 9

state the physical property that is used to separate the fractions of petroleum

Answer 9

the fractions have different boiling points

Question 10

which fraction of petroleum is used for paving road surfaces

Answer 10

bitumen

Question 11

which petroleum fraction has a lower boiling point - kerosene or naphtha

Answer 11

naphtha

[fractions higher up in the column have lower bp than those lower]

Question 12

which petroleum fraction is used as chemical feedstock

Answer 12

naphtha

Question 13

what is the general formula for alkanes

Answer 13

CnH2n+2

Question 14

what is the chemical formula for ethane

Answer 14

C2H6

Question 15

why are alkanes known as ‘saturated hydrocarbons’

Answer 15

they contain only single C-C covalent bonds

Question 16

why do the the mp/bp of alkanes increase down the homologous series (i.e. as molecular size of alkane increase)

Answer 16

stronger intermolecular forces of attraction between alkane molecules

Question 17

how does the viscosity of alkanes change

Answer 17

becomes more viscous as the alkane molecular size increase

Question 18

what are the products of complete combustion of alkanes

Answer 18

carbon dioxide and water/water vapour

Question 19

what is the general formula for alkenes

Answer 19

CnH2n

Question 20

why are alkenes known as ‘unsaturated hydrocarbons’

Answer 20

contain one or more C=C [or carbon-carbon double bond] (reject ‘carbon double bond’)

Question 21

state the catalysts used in catalytic cracking

Answer 21

aluminium oxide or silicon(IV) oxide (or silicon dioxide)

Question 22

what are the possible products of catalytic cracking

Answer 22

smaller alkenes and smaller alkanes and hydrogen gas

Question 23

what are the conditions for hydrogenation of alkenes

Answer 23

200 degree Celsius and Ni catalyst

Question 24

what is a major application of hydrogenation

Answer 24

to make margarine from vegetable oil

Question 25

what observation is seen when bromine is added to an alkene

Answer 25

reddish-brown bromine turns colourless (is decolourised)