Magnesium ribbon was added to 50 cm3 of 0.10 mol dm-3 hydrochloric acid at 20 °C. Curve R shows the volume of hydrogen collected. The experiment was then repeated three times, each with one change. Magnesium was in excess in every experiment.
Identify the curve, S, T or U, produced by each change.
(i) 50 cm3 of 0.20 mol dm-3 acid used
(ii) 50 cm3 of 0.050 mol dm-3 acid used
(iii) original acid used at 35 °C
[3]
Explain why curve U levels off at twice the volume of curve R.
[2]
Give the reason why curve S levels off at the same volume as curve R.
[1]