DP Chemistry (first assessment 2025)
Question 19M.1A.SL.TZ2.19
| Date | May 2019 | Marks available | [Maximum mark: 1] | Reference code | 19M.1A.SL.TZ2.19 |
| Level | SL | Paper | 1A | Time zone | TZ2 |
| Command term | Question number | 19 | Adapted from | N/A |
19.
[Maximum mark: 1]
19M.1A.SL.TZ2.19
Several reactions of calcium carbonate with dilute hydrochloric acid are carried out at the same temperature.
CaCO3 (s) + 2HCl (aq) → CaCl2 (aq) + H2O (l) + CO2 (g)
Which reaction has the greatest rate?
[1]
Markscheme
A
Examiners report
74 % of the candidates chose the correct combination to give the greatest rate of reaction. The most commonly chosen distractor was D where “smaller surface area of same mass of CaCO3(s)” was chosen. It seems these candidates confused “surface area” with “particle size”.
Syllabus sections
Reactivity 2. How much, how fast and how far? » Reactivity 2.2—How fast? The rate of chemical change » Reactivity 2.2.3—Factors that influence the rate of a reaction include pressure, concentration, surface area, temperature and the presence of a catalyst. Predict and explain the effects of changing conditions on the rate of a reaction.