DP Chemistry (first assessment 2025)
Question 19M.2.SL.TZ2.a
Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.2.SL.TZ2.a |
Level | SL | Paper | 2 | Time zone | TZ2 |
Command term | Explain | Question number | a | Adapted from | N/A |
a.
[Maximum mark: 2]
19M.2.SL.TZ2.a
Explain why, as the reaction proceeds, the pressure increases by the amount shown.
[2]
Markscheme
increase in the amount/number of moles/molecules «of gas» [✔]
from 2 to 3/by 50 % [✔]
Examiners report
Students were able in general to relate more moles of gas to increase in pressure.

Syllabus sections
Structure 1. Models of the particulate nature of matter » Structure 1.5—Ideal gases » Structure 1.5.1—An ideal gas consists of moving particles with negligible volume and no intermolecular forces. All collisions between particles are considered elastic. Recognize the key assumptions in the ideal gas model.