Question 1 · Higher Level
The graph shows the pH as 0.100 mol/L sodium hydroxide is added to 25.0 cm³ of ethanoic acid. What volume of sodium hydroxide reaches the equivalence point, and which indicator suits this titration?
Chemistry experiments and data questions
Learning outcomes that say investigate, determine or verify are practical work, and the written paper can ask about them. The skills are the same each time: variables, a fair test, processing results and a justified conclusion.
| Variables | Independent, dependent and controlled |
|---|---|
| Results | Moles, concentrations, titres, yields and rates |
| Quality | Repeatability, reproducibility, accuracy and error |
| Our practice | An experiment and data question in every section |
Name the variables first
Say what was changed, what was measured and what was kept the same, then say how it was kept the same. A control lets you see the effect of the variable you changed.
Use the numbers
When a question gives data, quote it: the value, the trend and any anomaly. Calculate moles, a concentration, a yield or a rate where it helps, with units.
Conclude only what the data shows
A conclusion answers the question the experiment asked and stays within the range tested. Suggest an improvement that would make the results more repeatable or more valid.
Try 2 questions
Question 2 · Both levels
| Time / s | Volume of CO₂ / cm³ |
|---|---|
| 0 | 0 |
| 10 | 24 |
| 20 | 42 |
| 30 | 54 |
| 40 | 61 |
| 50 | 64 |
| 60 | 65 |
| 70 | 65 |
Marble chips react with excess hydrochloric acid and the carbon dioxide is collected in a gas syringe. The table shows the results. What is the average rate of reaction over the first 30 s?
Next step
Questions people ask
Are there still mandatory experiments?
The new specification sets learning outcomes, some of which say investigate or determine. Your teacher plans the practical work that meets them.
Do I need to learn exact methods?
Know why each step is done. Questions often change the details, so understanding beats memorising.