A reaction in an open flask gives off a gas. A student records the mass of the flask and its contents every 10 s as the gas escapes.
Balance P gives readings to the nearest 0.1 g.
Balance Q gives readings to the nearest 0.01 g.
Both balances are zeroed before use and can measure the mass of the flask and its contents.
Why would using balance Q improve the measurements of reaction rate?
It can show smaller changes in mass between one reading and the next.
It will make the time of each reading more accurate, so the rate is more accurate.
It will make the gas escape more quickly, so the rate measured is higher.
It will record a larger total loss in mass because each reading has an extra decimal place.
127 exam-style questions on AQA GCSE Chemistry 6.1 Rate of reaction, covering 6.1.1a Calculating rates of reactions, 6.1.1b Gradient of a tangent as rate, 6.1.2 Factors which affect the rates of chemical reactions, 6.1.3 Collision theory and activation energy, and 6.1.4 Catalysts. Each one has a worked solution and a mark scheme showing where the marks go.