A research team investigates a reversible reaction between substances R and S. Changing R into S gives out 48 kJ of energy. The team then changes S back into R.
What happens to the energy during the change from S back into R, and why?
48 kJ is taken in, because the energy transfers are equal and opposite
48 kJ is given out, because both directions transfer energy to the surroundings
Less than 48 kJ is taken in, because some transferred energy has been used up
Less than 48 kJ is given out, because some energy escaped during the first change
109 exam-style questions on AQA GCSE Chemistry 6.2 Reversible reactions and dynamic equilibrium, covering 6.2.1 Reversible reactions, 6.2.2 Energy changes and reversible reactions, 6.2.3 Equilibrium, 6.2.4 The effect of changing conditions on equilibrium, 6.2.5 The effect of changing concentration, 6.2.6 The effect of temperature changes on equilibrium, and 6.2.7 The effect of pressure changes on equilibrium. Each one has a worked solution and a mark scheme showing where the marks go.