Equilibria

Question 1

What are the factors affecting:

Equilibria

Answer 1

• Increase in temperature -> shifts to endothermic side
• Increase in pressure -> shifts to side with least gas moles
• Increase in reactant -> shifts to other side

Question 2

What is an example of a:

Catalyst

Answer 2

Aluminium oxide (different)
silica (cracking)

Question 3

What are:

Catalysts?

Answer 3

• Speeds up the rate of reaction
• By providing an alternative pathway
• Which lowers the activation energy
• Does not get used up in the reaction

Question 4

What is a:

Reversible reaciton?

Answer 4

This is a reaction which can go both ways as the products can react to produce the original reactants

Question 5

Why can:

Reversible reactions be problematic?

Answer 5

Reduces the yield of product, so conditions must be chosen to shift the equilibrium towards the prodcuts

Question 6

What is a:

Dynamic equilibrium

Answer 6

• A reversible reaction where the:
• rate of the forward reaction = rate of the reverse reaction
• conentration of reactants + products is constant
• Happens in a closed system (so that no molecule may enter/leave)

Question 7

Examples of different:

Reversible reactions

Answer 7

1. Heating copper sulphate crystals
2. heating ammonium chloride
3. colbalt chloride

Question 8

Experiment:

Copper sulphate

Answer 8

Steps:
* Place 1 cm depth of hydrated copper sulphate in a boiling tube
* Heat till copper sulphate turns white (forward reaction)
* allow tube to cool for a few minutes
* add water with a pipette
* Copper sulphate should turn blue (backward reaction)

CuSO4.5H2O -> CuSO4 + 5H2O

Question 9

Practical:

Ammonium chloride

Answer 9

• Place 1cm of ammonium chloride in a test tube and put mineral wool to prevent gases from escaping
• Heat the ammonium chloride at the base at the base of the tube for a couple of minutes
• decomposes into 2 colourless gases so white solid disappears and reappears further up as the gases cool.

NH4Cl -> NH3 + HCl