DP Chemistry (last assessment 2024)
Question 19M.2.sl.TZ2.a(ii)
| Date | May 2019 | Marks available | [Maximum mark: 1] | Reference code | 19M.2.sl.TZ2.a(ii) |
| Level | sl | Paper | 2 | Time zone | TZ2 |
| Command term | State | Question number | a(ii) | Adapted from | N/A |
a(ii).
[Maximum mark: 1]
19M.2.sl.TZ2.a(ii)
Carbonated water is produced when carbon dioxide is dissolved in water under pressure.
The following equilibria are established.
Carbon dioxide acts as a weak acid.
The hydrogencarbonate ion, produced in Equilibrium (2), can also act as an acid.
State the formula of its conjugate base.
[1]
Markscheme
CO32– [✔]
Examiners report
A poorly answered question, though it discriminated very well between high-scoring and low-scoring candidates. Less than 40 % of the candidates were able to deduce the formula of the conjugate base of HCO3-. Wrong answers included water, the hydroxide ion and carbon dioxide.
