An effervescent tablet contains substances that react when the tablet is added to water. The reaction produces carbon dioxide gas.
A student adds one tablet to water in an open beaker. The student places the beaker on a piece of apparatus that measures mass. Carbon dioxide escapes from the beaker.
The table shows the student's results.
| Time (s) | Loss in mass (g) |
|---|---|
| 0 | 0.00 |
| 20 | 0.50 |
| 80 | 1.06 |
| 100 | 1.10 |
| 120 | 1.10 |
Name the piece of apparatus used to measure the mass.
Calculate the mass lost during each of these time intervals.
Give your answers in grams.
State which interval, 0 to 20 seconds or 80 to 100 seconds, has the greater mean rate of reaction.
A student makes this statement.
"The loss in mass stops changing after 100 seconds because carbon dioxide has no mass."
Explain why the student's statement is incorrect.
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.