A student investigated a reaction. The student repeated the reaction five times using the same method and measured the time taken for the reaction mixture to become cloudy.
| Repeat | Time in s |
|---|---|
| 1 | 41.7 |
| 2 | 42.1 |
| 3 | 58.0 |
| 4 | 42.3 |
| 5 | 41.9 |
Calculate the mean time and its uncertainty.
Give your answer in the form mean ± \pm\,± uncertainty.
A second student used the same method. The range of the second student's valid results was 1.2 s.
Explain which student's mean can be trusted more.
95 exam-style questions on AQA GCSE Chemistry 3.1 Chemical measurements, conservation of mass and the quantitative interpretation of chemical equations, covering 3.1.1 Conservation of mass and balanced chemical equations, 3.1.2 Relative formula mass, 3.1.3 Mass changes when a reactant or product is a gas, and 3.1.4 Chemical measurements. Each one has a worked solution and a mark scheme showing where the marks go.