A solid reactant is used to remove a dissolved substance during water treatment. The same mass of the solid can be supplied as a powder or compressed into one compact tablet.
The powder and tablet are placed in identical solutions at the same temperature. The tablet reacts at a lower rate.
Which change in the reacting particles explains the lower rate of the tablet?
Fewer solid particles are exposed, but collision frequency is unchanged and the proportion of successful collisions is lower.
Fewer solid particles are exposed, so collisions are less frequent and the proportion of successful collisions is higher.
Fewer solid particles are exposed, so collisions are less frequent and the proportion of successful collisions is lower.
Fewer solid particles are exposed, so collisions are less frequent and the proportion of successful collisions is unchanged.
122 exam-style questions on OCR GCSE Chemistry 5.2 Controlling reactions, covering 5.2.1 Measuring and interpreting rate of reaction, 5.2.2 Factors affecting rate and collision theory, and 5.2.3 Catalysts, activation energy and enzymes. Each one has a worked solution and a mark scheme showing where the marks go.