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Date May 2012 Marks available 2 Reference code 12M.2.SL.TZ1.3
Level Standard level Paper Paper 2 Time zone Time zone 1
Command term Define Question number 3 Adapted from N/A

Question

This question is about thermal energy transfer.

A hot piece of iron is placed into a container of cold water. After a time the iron and water reach thermal equilibrium. The heat capacity of the container is negligible.

Define specific heat capacity.

[2]
a.

The following data are available.

Mass of water = 0.35 kg
Mass of iron = 0.58 kg
Specific heat capacity of water = 4200 J kg–1K–1
Initial temperature of water = 20°C
Final temperature of water = 44°C
Initial temperature of iron = 180°C

(i) Determine the specific heat capacity of iron.

(ii) Explain why the value calculated in (b)(i) is likely to be different from the accepted value.

[5]
b.

Markscheme

the energy required to change the temperature (of a substance) by 1K/°C/unit degree;
of mass 1 kg / per unit mass;

a.

(i) use of mcΔT;
0.58×c×[180-44]=0.35×4200×[44-20];
c=447Jkg-1K-1≈450Jkg-1K-1;

(ii) energy would be given off to surroundings/environment / energy would be absorbed by container / energy would be given off through vaporization of water;
hence final temperature would be less;
hence measured value of (specific) heat capacity (of iron) would be higher;

b.

Examiners report

[N/A]
a.
[N/A]
b.

Syllabus sections

Core » Topic 3: Thermal physics » 3.1 – Thermal concepts
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