Alkanes

Question 1

Removal of carbon monoxide + nitrogen monoxide equation?

Answer 1

2NO + 2CO —–> N2 + 2CO2

Question 2

What are catalytic converters?

How does it do this?

Answer 2

Convert harmful gases into less harmful ones

Honeycomb structure increases surface area, increasing reaction rate

Question 3

What is flue gas desulfurisation?

What are the 2 equations to produce CaSO4?

Answer 3

Removal of sulphur dioxide

CaO + 2H2O + SO2 + 1/2O2 —-> CaSO4.2H2O

CaO3 + SO2 + 1/2O2 —-> CaSO4 + CO2

Question 4

What equation contributes to acid rain?

Answer 4

4NO2(g) + 2H2O(l) + O2 (g) —-> 4HNO3(g)

Question 5

What is the equation to make acid rain?

What problems does acid rain cause? (3)

Answer 5

SO2(g) + 1/2O2(g) + H2O —-> H2SO4

• Erosion of buildings
• Killing of plants
• Killing of fish through contamination of lakes

Question 6

What are the 2 types of cracking?

Answer 6

• Thermal
• Catalytic

Question 7

What is the pollutant effect on:

• CO2
• H2O
• CO
• Solid C

Answer 7

• Greenhouse gas
• Greenhouse gas
• Poisonous
• Damages the lungs

Question 8

What are the esssential features of fractional distillation to enable the crude oil to be seperated into fractions? (5)

Answer 8

• Crude oil is heated to vaporise + enters columns
• Hydrocarbons have different boiling points
• Boiling points depend on size/ Mr/ chain length
• Column is cooler at the top
• Larger molecules with higher boiling points condense at the bottom

Question 9

What is a fraction?

Answer 9

A mixture of compounds with similar boiling points + similar sized molecules

Question 10

Why does boiling point of alkanes increase as number of branches increases?

Answer 10

• More surface contact between molecules
• Induced dipole-dipole attractions are stronger

Question 11

Why does boiling point increase as carbon-chain length increases?

Answer 11

• Alkanes have induced dipole-dipole forces
• Strength of attraction increases with increasing size of molecule + number of electrons

Question 12

What’s the general formula for an alkene?

Answer 12

CnH2n

Question 12

How is the boiling point of an alkane determined by? (2)

Answer 12

• Carbon-chain length
• Number of branches (side-chains)

Question 13

• Complete combustion equation? How to balance?
• Incomplete combustion equation? Produce what types of products?

Answer 13

• Alkane + _O2 —–> _CO2 + _H2O

When balancing, do in alphabetical order

• Alkane + _O2 —–> _CO + _H2O = Produce gaseous products only
• Alkane + _O2 —–> _C + _H2O

Question 14

What are the conditions of catalytic cracking?

What does this produce?

Answer 14

• High temperature (lower than thermal): 720K
• Slight pressure: 100KPa
• Catalyst: Zeolite

Produces branched alkanes + clycoalkanes

Question 15

What are the conditions of thermal cracking?

What does thermal cracking produce?

Answer 15

• High temperature: 800-1200K
• High pressure: 7000KPa

Always an alkane with others being alkene

Question 16

Give 1 reason why carbon dioxide absorbs infrared radiation?

Answer 16

C=O bonds vibrate/are polar

Question 17

State 1environmental problem that NO causes?
What is used to remove NO from exhaust gases formed in petrol-fuelled cars?

Answer 17

• Acid rain
• Catalytic converters

Question 18

State what is meant by the term ‘carbon-neutral’?

Answer 18

No net emissions of CO2 to the atmosphere