DP Chemistry (first assessment 2025)
Question 19M.2.HL.TZ1.a
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.2.HL.TZ1.a |
| Level | HL | Paper | 2 | Time zone | TZ1 |
| Command term | Explain | Question number | a | Adapted from | N/A |
a.
[Maximum mark: 2]
19M.2.HL.TZ1.a
Explain how entropy affects this equilibrium.
[2]
Markscheme
entropy increases «and the reaction proceeds to the right» [✔]
more species / free molecules are formed
OR
more ways of distributing energy [✔]
Examiners report
There were several incorrect responses that products were more ordered than the reactants.
Syllabus sections
Reactivity 1. What drives chemical reactions? » Reactivity 1.4—Entropy and spontaneity (Additional higher level) » Reactivity 1.4.1—Entropy, S, is a measure of the dispersal or distribution of matter and/or energy in a system. The more ways the energy can be distributed, the higher the entropy. Under the same conditions, the entropy of a gas is greater than that of a liquid, which in turn is greater than that of a solid. Predict whether a physical or chemical change will result in an increase or decrease in entropy of a system. Calculate standard entropy changes, ΔS⦵, from standard entropy values, S⦵.