Question 22M.2.SL.TZ1.2a
| Date | May 2022 | Marks available | [Maximum mark: 2] | Reference code | 22M.2.SL.TZ1.2a |
| Level | SL | Paper | 2 | Time zone | TZ1 |
| Command term | Estimate, State | Question number | a | Adapted from | N/A |
Cold milk enters a small sterilizing unit and flows over an electrical heating element.
The temperature of the milk is raised from 11 °C to 84 °C. A mass of 55 g of milk enters the sterilizing unit every second.
Specific heat capacity of milk = 3.9 kJ kg−1 K−1
Estimate the power input to the heating element. State an appropriate unit for your answer.
[2]
energy required for milk entering in 1 s = mass x specific heat x 73 ✓
16 kW OR 16000 W ✓
MP1 is for substitution into mcΔT regardless of power of ten.
Allow any correct unit of power (such as J s-1 OR kJ s-1) if paired with an answer to the correct power of 10 for MP2.
Most candidates recognized that this was a specific heat question and set up a proper calculation, but many struggled to match their answer to an appropriate unit. A common mistake was to leave the answer in some form of an energy unit and others did not match the power of ten of the unit to their answer (e.g. 16 W).
