DP Chemistry (last assessment 2024)
Question 18M.2.sl.TZ2.a
| Date | May 2018 | Marks available | [Maximum mark: 3] | Reference code | 18M.2.sl.TZ2.a |
| Level | sl | Paper | 2 | Time zone | TZ2 |
| Command term | Show, Sketch | Question number | a | Adapted from | N/A |
a.
[Maximum mark: 3]
18M.2.sl.TZ2.a
Graphing is an important tool in the study of rates of chemical reactions.
Sketch a Maxwell–Boltzmann distribution curve for a chemical reaction showing the activation energies with and without a catalyst.
[3]
Markscheme
both axes correctly labelled
correct shape of curve starting at origin
Ea(catalyst) < Ea(without catalyst) on x-axis
M1:
Accept “speed” for x-axis label.
Accept “number of particles”, “N”, “frequency” or “probability «density»” for y-axis label.
Do not accept “potential energy” for x-axis label.
M2:
Do not accept a curve that touches the x-axis at high energy.
Do not award M2 if two curves are drawn.
M3:
Ignore any shading under the curve.
[3 marks]