Topic 4: Haber process + Rate of attainment

What does the Haber process involve

• it involves the reversible reaction between nitrogen and hydrogen to form ammonia gas

• it is the industrial process used to produce ammonia gas

What type of reaction is the reaction between nitrogen and hydrogen which takes place in the Haber process

exothermic reaction (therefore the forwards reaction is exothermic)

Why are the gases hydrogen and nitrogen hard to react?

because nitrogen is very uncreative as it has a very strong triple bond

what is the process from which nitrogen is obtained?

fractional distillation

what is the raw material nitrogen comes from?

the air

What is the raw material hydrogen is from?

natural gases

What is the equation for the reaction between natural gas and steam to produce hydrogen?

methane + water vapoour → hydrigen + carbon dioxide

NH4 + H2O → 3H2 + CO2

What is the name of the area in the reactor where the main reaction to produce ammonia takes place

Convertor

What is the name of the catalyse used?

iron

Which temperature conditions would give the best yield of ammonia?

lower temperature, because the forward reaction is exothermic

Why are these temperature conditions (low temperatures) NOT used ?

Because the rate of reaction would be too slow

What pressure is used in the Haber process?

200 atmospheres

What temperature is used in the Haber process?

450 degrees

What 3 things come out of the converter in the Haber process?

hydrogen gas, nitrogen gas and ammonia gas - H2, N2, NH3

What happens to these gases when they come out?

they are cooled

What happens to ammonia after it is cooled?

it turns from a gas to a liquid (condenses) this is because it has a higher melting point than H2 and N2

What happens to the unreacted hydrogen and nitrogen in the converter?

they are recycled and are fed back into the converter

What conditions would give the best yield of ammonia ? why aren’t these conditions used?

• low temperature

• high pressure

low temperatures give a slow rate of reaction

high pressure is expensive to create and can be dangerous

What are the actual conditions that are used in the Haber process? and why aren’t the

• a higher temp of 450 degrees

• 200 atmospheres

Here is a labelled diagram of the Haber process

What factors affect the rate of attainment of equilibrium?

• temperature

• Pressure/ Volume for gases and Concentration for aqueous solutions

• Surface Area

• catalyst

These factors affect the rate of the forwards and reverse reactions equally

What affect would any factor that increased the rate of the forwards reaction have on the reverse reaction?

it would increase the rate of the reverse reaction by the same amount and decrease the time taken to reahequilibrium

What affect would any factor that decreases the rate of the forwards reaction have on the reverse reaction?

it would decrease the rate of the reverse reaction by the same amount and increase the time taken to reach equilibrium

When a approaching questions about the rate of attainment use…?

the collision theory