DP Chemistry (first assessment 2025)
Question 19N.2.SL.TZ0.4a(ii)
| Date | November 2019 | Marks available | [Maximum mark: 1] | Reference code | 19N.2.SL.TZ0.4a(ii) |
| Level | SL | Paper | 2 | Time zone | TZ0 |
| Command term | Justify, State | Question number | a(ii) | Adapted from | N/A |
a(ii).
[Maximum mark: 1]
19N.2.SL.TZ0.4a(ii)
(a(ii))
The value of the equilibrium constant for the first dissociation at 298 K is 5.01 × 10−4.
State, giving a reason, the strength of citric acid.
[1]
Markscheme
weak acid AND partially dissociated
OR
weak acid AND equilibrium lies to left
OR
weak acid AND Kc/Ka<1 ✔
Syllabus sections
Reactivity 3. What are the mechanisms of chemical change? » Reactivity 3.1—Proton transfer reactions » Reactivity 3.1.6—Strong and weak acids and bases differ in the extent of ionization. Recognize that acid–base equilibria lie in the direction of the weaker conjugate. and are strong acids, and group 1 hydroxides are strong bases.
Reactivity 2. How much, how fast and how far? » Reactivity 2.3—How far? The extent of chemical change » Reactivity 2.3.2—The equilibrium law describes how the equilibrium constant, K, can be determined from the stoichiometry of a reaction. Deduce the equilibrium constant expression from an equation for a homogeneous reaction.