CfE Higher Chemistry - Rates of Reaction

A small increase in temperature results in a large increase in rate of reaction.

The main reason for this is that

• more high energy collisions are taking place

• the enthalpy change is lowered

• the activation energy is lowered

• many more particles have energy that exceeds the activation energy

The activation energy for the reverse reaction is

• X

• X - Y

• Z - Y

• Y

The enthalpy change for the forward reaction can be defined as

• Z - Y

• X - Z

• Y - Z

• Z

The potential energy diagram below refers to the reversible reaction involving reactants R and products P. What is the enthalpy change, in kJmol^-, for the reverse reaction P→ R?

• +30

• +10

• -10

• +80

Temperature is a measure of

• heat

• the activation energy

• exothermic reations

• average kinetic energy of a substances molecules

The denaturing of an enzyme could be represented by which of the following graphs

• 
• 
• 
• 

In area X

• Molecules always form an activated complex

• No molecules have the energy to form an activated complex

• Collisions between molecules are always successful in forming products

• All molecules have the energy to form an activated complex

When a catalyst is used, the activation energy of the forward reaction is reduced to 35 kJ mol^–1. What is the activation energy of the catalysed reverse reaction?

• 30 kJ mol^–1

• 35 kJ mol^–1

• 65 kJ mol^–1

• 180 kJ mol^–1

What was the reaction time, in seconds, when the concentration of the reactant was 0.50 mol l^–1?

• 0.2

• 0.5

• 2.0

• 5.0

Which of the following is correct for the reverse reaction?

• Endothermic - Ea +120

• Exothermic - Ea +20

• Endothermic - Ea +80

• Exothermic - Ea +80