DP Chemistry (last assessment 2024)
Question 18M.2.hl.TZ1.2b
| Date | May 2018 | Marks available | [Maximum mark: 2] | Reference code | 18M.2.hl.TZ1.2b |
| Level | hl | Paper | 2 | Time zone | TZ1 |
| Command term | Describe | Question number | b | Adapted from | N/A |
b.
[Maximum mark: 2]
18M.2.hl.TZ1.2b
Calcium carbide, CaC2, is an ionic solid.
(b)
Describe how the relative atomic mass of a sample of calcium could be determined from its mass spectrum.
[2]
Markscheme
multiply relative intensity by «m/z» value of isotope
OR
find the frequency of each isotope
sum of the values of products/multiplication «from each isotope»
OR
find/calculate the weighted average
Award [1 max] for stating “m/z values of isotopes AND relative abundance/intensity” but not stating these need to be multiplied.
[2 marks]
