CHAPTER 9: QUANTITY OF HEAT

Heat is a form of energy that flows from a hotter object to a colder object. This chapter quantifies that energy. We explore how much heat is needed to raise the temperature of a substance (specific heat capacity) and how much is needed to change its state (latent heat). The method of mixtures is our experimental tool for measuring these quantities. This knowledge is essential for engineers, meteorologists, cooks, and anyone who wants to understand energy transfer.

9.1 HEAT CAPACITY AND SPECIFIC HEAT CAPACITY

When you add heat to an object, its temperature rises. The amount of rise depends on how much heat you add, the mass of the object, and the material it's made of.

9.1.1 Heat Capacity (C)

Heat capacity (also called thermal capacity) is the amount of heat energy required to raise the temperature of an entire object by 1°C (or 1 K).

Heat Capacity (C) = Q / Δθ

Where:

• C = heat capacity (in J/°C or J/K)
• Q = heat energy supplied (in Joules, J)
• Δθ = change in temperature (in °C or K)

Heat capacity depends on both the material and the mass of the object. A large object made of the same material as a small object will have a larger heat capacity.

9.1.2 Specific Heat Capacity (c)

Specific heat capacity is a property of the material itself, independent of the mass. It is the amount of heat energy required to raise the temperature of 1 kg of t