A laboratory worker adds water to a reactant solution before mixing it with a second solution. The water does not react and the temperature stays constant. How does adding the water usually affect the reaction rate?
It adds particles to the mixture, making successful collisions between reactants more frequent.
It makes the reaction faster because a larger volume of mixture can form more product.
It spreads the reactant particles through a larger volume, making their collisions less frequent.
It leaves collision frequency unchanged because the number of reactant particles has not changed.
122 exam-style questions on Edexcel GCSE Chemistry 8.1 Rates of reaction, covering 8.1.1 Measuring and interpreting rates of reaction, 8.1.2 Collision theory and the factors affecting rate, and 8.1.3 Catalysts and enzymes. Each one has a worked solution and a mark scheme showing where the marks go.