chemistry

Question 1

What is a homologous series?

Answer 1

Group of compounds with same general formula

Question 2

What are isomers?

Answer 2

Molecules with same molecular formula but different structures

Question 3

What’s the formula for alkanes?

Answer 3

CnH2n+2

Question 4

What does saturated mean?

Answer 4

Single bonds so no more can be added (alkanes)

Question 5

What’s the formula for alkenes?

Answer 5

CnH2n

Question 6

What does unsaturated mean?

Answer 6

Double bond can open up to allow new bonds to form

Question 7

What are the products of complete combustion of alkanes?

Answer 7

alkane + oxygen –> carbon dioxide + water

Question 8

What are the products of complete incomplete combustion of alkanes?

Answer 8

carbon + carbon monoxide + carbon dioxide + water

Question 9

What happens when halogens reacts with alkanes?

Answer 9

Hydrogen atom is replaced by chlorine or bromine (substitution). Needs UV light.

Question 10

What happens when halogens react with alkenes?

Answer 10

Double carbon bond is split and two halogen atoms added (addition reaction) eg bromine + ethane –> dibromoethane.

Question 11

What is test for alkenes (double carbon bonds)?

Answer 11

Bromine water + alkene goes from orange to colourless

Question 12

What is cracking?

Answer 12

Splitting up of long chain hydrocarbons. Thermal decomposition (breaking molecules into simpler molecules by heating)

Question 13

Why is cracking used?

Answer 13

More demand for short chain hydrocarbons eg in petrol and chemical industry, so longer chain hydrocarbons are split

Question 14

What are the conditions needed for cracking?

Answer 14

A catalyst (silica or alumina) and heat (600 - 700 degrees)

Question 15

What is an addition polymer?

Answer 15

Made up of carbon double bond monomers Need high pressure to form