A student investigates how temperature affects the rate of reaction between magnesium ribbon and dilute hydrochloric acid.
She adds a 2.0 cm length of magnesium ribbon to a beaker of dilute hydrochloric acid and measures the time taken for the magnesium ribbon to completely react and disappear. She repeats this experiment at five different temperatures.
The table shows her results:
| Temperature in ∘C{^\circ}\text{C}∘C | 15 | 25 | 35 | 45 | 55 |
|---|---|---|---|---|---|
| Time taken in seconds | 150 | 95 | 60 | 38 | 24 |
Describe the relationship shown by the results between temperature and the time taken for the magnesium ribbon to disappear.
Estimate the time taken for the magnesium ribbon to disappear at 30 ∘C30\ {^\circ}\text{C}30 ∘C.
Explain, in terms of particles, why an increase in temperature increases the rate of this reaction.
State one variable (other than the length of the magnesium ribbon) that must be kept constant for the experiment to be valid.
