When a catalyst is involved in the collision between the reactant molecules, more energy is required.

What is the term used to refer to the number of collisions per unit volume of the reaction mixture?

For the reaction shown in the equation below the fastest reaction will occur between ...

2HCl (aq) + CaCO₃ (s) $$\rightarrow$$   CaCl₂ (aq) + H₂O (l) + CO₂(g)

The diagram shows the energy profile of a reversible reaction that occurs with and without a catalyst.

What can be deduced from the diagram?

I. The enthalpy change for the forward catalysed reaction —20 kJ/mol.

II. The catalysed backward reaction is endothermic.

III. The enthalpy change is decreased by using catalyst.

IV. The activation energy for the backward uncatalysed reaction is 80 kJ/mol

Magnesium needs to be heated before it reacts with oxygen in the air. What conclusion can you draw from this?

Which of the following statements correctly explains why a reaction is endothermic?

Which of the following reactions releases most energy to the surroundings?

Products will form faster if __________

Given the reaction:    

2 SO₂ (g) + O₂ (g) $$\rightarrow$$   2 SO₃ (g) 

The rate of the forward reaction increases by adding more SO₂ because the ….