Topic 4b- Equilibria (paper 1)

Question 1

What is a reversible reaction?

Answer 1

A reaction in which the products themselves can react to produce the original reactants.

Question 2

What is dynamic equilibrium?

Answer 2

When the amounts of products and reactants reach a balance- their concentrations stop changing.

Question 3

What is a closed system?

Answer 3

Where none of the reactants or products can escape and nothing else can get in

Question 4

What three things can change the position of equilibrium?

Answer 4

Temperature
Pressure
Concentration of products or reactants

Question 5

What temperature and pressure is the Haber Process carried out at?

Answer 5

200 atm
450°C

Question 6

What is Le Chatelier’s principle?

Answer 6

The idea that when you change the conditions of a reversible reaction at equilibrium, the system will counteract this change.

Question 7

What are the key points in manufacturing fertilizer industrially?

Answer 7

• The NH3 and H2SO4 are imported on large scale (tonnes)
• The reactants are continuously piped into large reaction towers were concentrated sulphuric acid is sprayed into ammonia gas at 60°C
• A slurry of ammonium sulphate is blown through hot air to produce small pellets of the fertiliser.

Question 8

How is ammonium sulphate prepared in the laboratory?

Answer 8

1. Set up equipment as shown [draw a diagram of a titration- burette containing dilute suplhuric acid with a connical flask containing ammonia solution and an methyl orange indicator]
2. Slowly add the dilute sulphuric acid to the ammonia until the solution changes to red.
3. Go especially slowly when close to the end point
4. Since this sample is not pure (it contains methyl orange) this must be redone using the exact same quantities.
5. To get solid ammonium sulphate crystals, gently evapourate the solutions using a steam bath until only a little remains
6. Leave it to crystalise before filtering the crystals and leave them to dry.

Question 9

What is the reaction in the haber process to produce fertiliser?

Answer 9

NH3(aq) + HNO(aq) → NH4NO3(aq)