Calorimetry experiments for determining the enthalpy changes of reactions
4 marks · NormalThe table shows some data from a calorimetry experiment measuring the enthalpy change of a displacement reaction between iron and copper(II) sulfate:
| Volume of copper(II) sulfate solution / cm³ | Mass of iron used / g | Initial temperature / °C | Maximum temperature / °C | Specific heat capacity / J/g°C |
|---|---|---|---|---|
| 60 | 2.4 | 18.4 | 24.7 | 4.18 |
Calculate the temperature change (ΔT) for this reaction.
Assume the density of the solution is 1 g/cm³. Calculate the heat energy change, Q, in joules.
Suggest one assumption made in this calculation.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) 6.3 °C
(b) 1579 J
(c) Assuming the specific heat capacity of the solution is the same as that of water.
Common mistakes: not converting units; using mass of Fe instead of solution
Show mark scheme and worked solution
Marking points
A1 (a) · 1 mark · Correct calculation of ΔT: 24.7 - 18.4 = 6.3°C
M1 (b) · 1 mark · Substitutes correct mass (60 g), s.h.c. (4.18), and ΔT (6.3) into Q = mcΔT. (follow-through)
A2 (b) · 1 mark · Obtains Q = 60 × 4.18 × 6.3 = 1579 J (accept small rounding errors). (follow-through)
B1 (c) · 1 mark · Suggests any suitable assumption, e.g., s.h.c. same as water, density same as water, all heat goes to solution.
Worked solution
(a) ΔT = 24.7 - 18.4 = 6.3°C
(b) Q = mcΔT = 60 g × 4.18 J/g°C × 6.3°C = 1579 J
(c) One assumption is that the specific heat capacity of the solution is the same as water's.