The interhalogen compound BrF₃ is a volatile liquid which autoionises.

The Contact process is used in the manufacture of sulfuric acid. The equation for the main reaction is shown below.

R and S react together.

1 the activation energy of the reaction

2 the enthalpy change of the reaction

3 the equilibrium constant of the reaction

The equilibrium constant, K_c, for the reaction shown is 2 mol^–2 dm⁶, at 600 K.

Hydrogen and carbon dioxide gases are mixed in equal molar amounts at 800K. A reversible reaction takes place.

The formation of hydrogen and ethyne, C₂H₂, from methane reaches dynamic equilibrium.

The reaction

is catalysed by platinum.

Which statements about the properties of the catalyst are correct?

1 The catalyst has no effect on the enthalpy change of the reaction.

2 The catalyst increases the rate of the reverse reaction.

3 The catalyst increases the average kinetic energy of the reacting particles.

In an experiment, 2.00 mol of hydrogen and 3.00 mol of iodine were heated together in a sealed container and allowed to reach equilibrium at a fixed temperature. The container had a fixed volume of 1.00 dm³. At equilibrium, there were 2.40 mol of iodine present in the mixture.

Which statements about reversible reactions are correct?

1 An increase in concentration of a reactant always increases the concentration of the product.

2 An increase in temperature always increases the rate at which the equilibrium is established.

3 An increase in temperature always increases the concentration of the product at equilibrium.

Nitrogen and hydrogen can react together to form ammonia.

The formation of ammonia is exothermic.

The rate and yield of the reaction can be altered by changing the conditions under which the reaction is carried out.

Which row shows the effects of adding iron to the mixture and increasing the temperature?

The equation represents an equilibrium.

1 a reduction in the reaction temperature

2 the use of a suitable catalyst

3 an increase in the total pressure