C9 - Crude Oil and Fuels

Question 1

define:

hydrocarbon

Answer 1

molecules made from hydrogen and carbon

Question 2

describe

properties of hydrocarbons as polymers become longer

Answer 2

• boiling point = increases
• viscosity = increases
• flammability = decreases

Question 3

word equation

combustion of hydrocarbon

Answer 3

oxygen + hydrocarbon → carbon dioxide + water

Question 4

method used to seperate crude oil

Answer 4

fractional distillation

Question 5

testing for carbon dioxide

combustion of hydrocarbon

Answer 5

limewater - turns cloudy/milky

Question 6

substance formed in incomplete combustion

Answer 6

carbon monoxide

Question 7

testing for water

combustion of hydrocarbon

Answer 7

blue cobalt chloride paper in a U tube - turns pink

Question 8

define

cracking

Answer 8

breaking large hydrocarbon molecules down into smaller molecules

Question 9

list and describe

2 processes of cracking

Answer 9

• catalytic cracking - passed over a hot catalyst (550)
• steam cracking - mixed with steam to a very high temperature (800)

Question 10

define

unsaturated hydrocarbon

Answer 10

a hydrocarbon that has atleast one C=C double bond, like an alkene

or a C≡C triple bond

Question 11

test for alkenes (unsaturated)

Answer 11

orange bromine water - turns colourless

Question 12

Are alkenes more or less reactive than alkanes?

Answer 12

alkenes > alkanes

in terms of reactivity

Question 13

Why is cracking useful?

Answer 13

Large hydrocarbons have little use, so cracking breaks them down into more useful smaller molecules that are used for fuels