A student uses this apparatus to investigate the rate of the reaction between zinc and an excess of dilute hydrochloric acid.
This is the student’s method.
- pour 50 cm3 of dilute hydrochloric acid into a conical flask
- add about 1.2 g of zinc lumps
- record the volume of hydrogen gas collected every 30 s until no more hydrogen is collected
The graph shows the student’s results.
i)
Calculate the mean (average) rate of reaction, in cm3 / s, in the first 120 s.
(2)
mean rate = .............................................................. cm3 / s
ii)
The equation for the reaction between zinc and hydrochloric acid is
Zn (s) + 2HCl (aq) → ZnCl2 (aq) + H2 (g)
Use this equation and the particle collision theory to explain why the rate of reaction is greatest at the start of the reaction.
(3)
iii)
The student repeats the experiment at a higher temperature but keeps all other conditions the same.
On the grid, draw the curve you would expect to see in this experiment.
(2)
iv)
Explain why the rate of reaction is greater if the same mass of zinc powder is used instead of zinc lumps. All other conditions are kept the same.
(2)