Pupil sheet · Rates of reaction
Rates of reaction — return questions
Name ______________________ Date ____________
Use one to two weeks after the lessons. Keep the notes and the lesson closed.
1. identify
Supplement. Pupils plan how to follow the rate of a reaction that makes a gas. Which row gives a plan that will work well?
| Row | Gas made in total | How the pupil follows it |
|---|---|---|
| A | about 50 cm³ (0.004 g) of hydrogen | loss of mass, on a balance that reads to 0.01 g |
| B | about 270 cm³ (0.50 g) of carbon dioxide | volume, in a 100 cm³ gas syringe |
| C | about 270 cm³ (0.50 g) of carbon dioxide | loss of mass, on a balance that reads to 0.01 g |
| D | about 270 cm³ (0.50 g) of carbon dioxide | loss of mass, on a balance that reads to 1 g |
Circle one answer.
- A
- B
- C
- D
2. calculate
Sodium carbonate powder reacts with dilute nitric acid, and the carbon dioxide is collected in a gas syringe. Over the first 35 s the average rate is 1.4 cm³/s. (a) Calculate the volume of gas collected in the first 35 s. (b) In a second experiment, 66 cm³ of gas is collected at an average rate of 1.2 cm³/s. Calculate the time taken.
(a) Volume in the first 35 s: ______________ unit ________
(b) Time taken: ______________ unit ________
3. explain / give
A car's catalytic converter holds a thin layer of platinum. It speeds up reactions that turn harmful exhaust gases into less harmful ones, and the same platinum keeps working for years. (a) Explain how this shows that platinum is a catalyst. (b) Supplement. Explain, using activation energy, how the platinum speeds up the reactions. (c) Supplement. The converter works poorly until the hot exhaust has warmed it up. Give two reasons, using collision theory, why the reactions are faster when it is hot. (d) The platinum is spread over a honeycomb (a block full of tiny channels with very thin walls) instead of being one solid lump. Explain why this makes the reactions faster.
(a) Why it is a catalyst
(b) Supplement: activation energy
(c) Supplement: two reasons
(d) The honeycomb
4. explain
Supplement. Acid rain slowly wears away limestone, which is calcium carbonate. Where the rain is more acidic, with more concentrated acid, the stone wears away faster. Which statement explains why?
Circle one answer.
- More acid particles in the same volume, so they collide with the stone more often
- The acid particles are bigger, so they hit the stone harder
- More concentrated acid lowers the activation energy
- The acid particles move faster, so every collision succeeds