DP Chemistry (last assessment 2024)
Question 19M.2.hl.TZ1.4d
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.2.hl.TZ1.4d |
| Level | hl | Paper | 2 | Time zone | TZ1 |
| Command term | Calculate | Question number | d | Adapted from | N/A |
d.
[Maximum mark: 2]
19M.2.hl.TZ1.4d
This question is about the decomposition of hydrogen peroxide.
(d)
Sodium percarbonate, 2Na2CO3•3H2O2, is an adduct of sodium carbonate and hydrogen peroxide and is used as a cleaning agent.
Mr (2Na2CO3•3H2O2) = 314.04
Calculate the percentage by mass of hydrogen peroxide in sodium percarbonate, giving your answer to two decimal places.
[2]
Markscheme
M( H2O2) «= 2 × 1.01 + 2 × 16.00» = 34.02 «g» [✔]
«% H2O2 = 3 × × 100 =» 32.50 «%» [✔]
Note: Award [2] for correct final answer.
Examiners report
It is recommended that candidates use the relative atomic masses given in the periodic table.
