Measuring heat energy
4 marks · Normal| Material | Mass (kg) | Specific Heat Capacity (J/kg°C) | Temperature increase (°C) |
|---|---|---|---|
| A | 0.5 | 800 | 10 |
| B | 0.5 | 400 | 20 |
For material A, calculate the energy required to raise its temperature by 1 °C.
Explain, using data from the table, why material B's temperature increases more than material A's when they are supplied with the same energy.
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.
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(a) 400 J · must show 0.5 x 800
(b) Material B has a lower specific heat capacity (400 J/kg°C) than A (800 J/kg°C), so for the same energy and mass, it undergoes a greater temperature rise. Less energy is needed for each degree increase in temperature. · must show B lower s.h.c., greater temp rise for same energy
Common mistakes: Incorrect multiplication in a; Ignoring mass in calculation
Show mark scheme and worked solution
Marking points
A1 (a) · 1 mark · Correct calculation: 0.5 kg x 800 J/kg°C = 400 J per °C.
B1 (b) · 1 mark · Links lower specific heat capacity for B to its larger temperature rise.
B2 (b) · 1 mark · Compares s.h.c. for both materials with data.
B3 (b) · 1 mark · States less energy needed per degree for B so temperature increases more for same energy.
Worked solution
a) Energy for 1°C rise for A = mass × s.h.c. = 0.5 kg × 800 J/kg°C = 400 J
b) Material B needs less energy to raise its temperature by 1°C (0.5 × 400 = 200 J), so with the same energy (4,000 J), B's temperature increases more. The lower the specific heat capacity, the larger the temperature change for the same energy.