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Lesson: Chapter 9 — Heat

Heat capacity 1 of 2

The heat capacity of an object

Does the same amount of heat raise every substance's temperature by the same amount? Activity 9.2 tests it.

Activity 9.2

You will need: three identical beakers, water, coconut oil, three thermometers, three identical Bunsen burners, a stirrer

  1. Put a measured volume of water in one beaker, the same volume of coconut oil in the second, and twice that volume of water in the third.
  2. Measure all three temperatures.
  3. Heat all three over identical burners for the same time, about 5 minutes, and measure the temperatures again.

Figure to be added

Figure 9.10 — water, coconut oil and twice as much water heated over three identical burners.

The observation

All three got about the same heat, yet their temperatures rose by different amounts. Different amounts of the same substance, and the same amounts of different substances, warm differently for the same heat: their heat capacities differ.

Heat capacity

The heat capacity of an object is the heat needed to raise its temperature by one unit. Its SI unit is J K-1; it can also be given in J °C-1. It is written C.

An object's heat capacity depends on what it is made of and on its mass. Objects of one material but different masses have different heat capacities; objects of equal mass but different materials can too.