3a.3 - Reversible Reactions, The Haber Process, Alcohols, Carboxylic Acids and Esters Flashcards
What is a reversible reaction?
A reaction where the products of the reaction can themselves react to produce the original reactants
What will reversible reactions eventually reach?
Equilibrium
What does a reversible reaction take place in?
A closed system
What is equilibrium?
The amounts of reactants and products will reach a certain balance and stay there
What will happen in terms of yield if the forward reaction is exothermic and the temperature is raised? (3)
- The equilibrium will shift to the left
- Because increasing the temperature will favour the endothermic reaction
- So yield will decrease
What will happen in terms of yield if the forward reaction is endothermic and the temperature is raised? (3)
- Equilibrium shifts to the right
- Favours endothermic reaction
- Yield increases
What will happen in terms of yield if the forward reaction is exothermic and the temperature is reduced? (3)
- Equilibrium shifts to right
- Favours exothermic reaction
- Yield decreases
What will happen in terms of yield if the forward reaction is endothermic and the temperature is reduced? (3)
- Equilibrium shifts to left
- Favours exothermic reaction
- Yield decreases
Why will the yield increase as the temperature is raised in an endothermic reaction?
To take in and use up the extra heat
Why will the yield increase as the temperature is reduced in an exothermic reaction?
To give out more heat
What will happen in terms of yield if the forward reaction has more molecules and the pressure is raised? (3)
- Equilibrium shifts left
- Favours side with least molecules
- Yield decreases
What will happen in terms of yield if the forward reaction has less molecules and the pressure is raised? (3)
- Equilibrium shifts right
- Favours side with least molecules
- Yield increases
What will happen in terms of yield if the forward reaction has more molecules and the pressure is reduced? (3)
- Equilibrium shifts right
- Favours side with most molecules
- Yield increases
What will happen in terms of yield if the forward reaction has less molecules and the pressure is reduced? (3)
- Equilibrium shifts left
- Favours side with most molecules
- Yield decreases
What does a catalyst do? (2)
- Speeds up both forward and backwards reaction by the same amount
- Reaches equilibrium quicker
Where does the nitrogen come from for the Haber process?
From the air
Where does the hydrogen come from for the Haber process?
Natural gas or crude oil
What are the uses of ammonia? (3)
- Fertilisers
- Textiles
- Explosives
What is the pressure used in the Haber process?
200 atmospheres
What is the temperature used in the Haber process?
450C
What is the catalyst used in the Haber process?
Iron
Why is a compromise made with the pressure? (5)
- High pressure favours forward reaction
- So pressure needs to be high
- Expensive to have a plant operating at high pressures
- Cheaper to have low pressures
- Compromise is made
Why is a compromise made with the temperature? (5)
- Low temperatures favour exothermic reactions
- So temperature needs to be low
- Rate of reaction is lower at lower temperatures
- Make more money faster with higher temperature
- Compromise is made
Describe the Haber process (4)
- H2 and N2 mixed in 3:1 ratio
- Goes through cylinder with trays of iron catalyst
- Unused H2 and N2 is recycled so nothing is wasted
- Cools in condenser
