Why is 1/t 1/t\,1/t a useful comparative rate when the same visible endpoint is used each time?
It shows the total amount of product, so a larger value means more product
The same change occurs each time, so a shorter time means a faster rate
Rate is directly proportional to time, so a longer time means a faster rate
It gives the rate at the instant the cross disappears, not an average rate
127 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.