Alkanes

Question 1

What does it mean when a molecule is saturated ?

Answer 1

Only has single bonds.

Question 2

Why are the IMF between 2-methyl propane weaker than Propane ?

Answer 2

Methyl group decreases the surface contact between molecules so the VDW forces are much weaker.

Question 3

What is the definition of a fraction ?

Answer 3

A mixture of compounds with similar boiling points and similar sized molecules.

Question 4

What is the purpose of fractional distillation ?

Answer 4

Separating crude oil into fractions.

Question 5

Explain the process of fraction distillation.

Answer 5

Crude oil is heated until it is vaporized and enters the column
Larger hydrocarbons have higher BP
Smaller hydrocarbons have lower BP
Column is cooler at top so smaller hydrocarbons condense at top and large condense at bottom

Question 6

What is the cracking and why do we do it ?

Answer 6

Cracking is breaking up large hydrocarbon chains into smaller ones.
Smaller hydrocarbons have higher demand.

Question 7

What are the two types of cracking ?

Answer 7

Catalytic and thermal.

Question 8

What are the conditions for thermal cracking ?

Answer 8

High temperature - 700-1200K
High pressure - 7000KPa

Question 9

What are the products of thermal cracking ?

Answer 9

One alkane and multiple alkenes.

Question 10

What are the conditions of catalytic cracking ?

Answer 10

High temperature - 720K
Slight pressure - 100KPa
catalyst - Zeolite

Question 11

What are the products of complete combustion ?

Answer 11

Water and Carbon dioxide

Question 12

What are the 2 possible products of incomplete combustion ?

Answer 12

Carbon monoxide and water
Soot (Solid C) and water

Question 13

What are the additional pollutants that can be caused by combustion of alkanes ?

Answer 13

Sulphur dioxide
Nitrogen oxide (and multiples e.g. NO2 NO4)

Question 14

What are the formulae for production of acid rain ?

Answer 14

4NO2 + 2H2O + O2 ===> 4HNO3
SO2 + 0.5O2 + H2O ===> H2SO4

Question 15

What are the formulae for flue gas desulphurization ?

Answer 15

CaO + H2O + SO2 + 0.5O2 ===> CaSO4.H2O
CaCO3 + 0.5O2 + SO2 ===> CaSO4 + CO2

Question 16

What is the purpose of catalytic converters ?

Answer 16

Remove harmful gasses produced from the combustion of fuel in engines.

Question 17

What are properties of catalytic converters that make them work ?

Answer 17

Honeycomb structure for large surface area
Platinum and Rhodium metals to act as catalysts.

Question 18

What is the equation of removal of carbon monoxide and nitrogen oxide from catalytic converters ?

Answer 18

2NO(g) + 2CO(g) ==> N2(g) + 2CO2(g)