Lesson Notes By Weeks and Term v4 - SHS 2

Lesson Video

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Performance objectives

• Define specific heat capacity.
• Describe how to find the specific heat capacity of a solid.
• Perform calculations using the heat transfer formula.
• Relate heat concepts to real-life situations in Ghana.

Lesson summary

This lesson introduces the experimental method used to determine the specific heat capacity of a solid, a fundamental property of matter. Understanding this concept helps us explain everyday phenomena, such as why the sand at Labadi beach gets very hot under the sun while the sea water remains cool, or why a metal spoon in a hot bowl of soup heats up much faster than the ceramic bowl itself. This procedure, known as the "Method of Mixtures," is a practical application of the principle of conservation of energy.

Lesson notes

A. Review of Key Terms Heat (Q): A form of energy that is transferred from a body at a higher temperature to a body at a lower temperature. Its S.I. unit is the Joule (J). Temperature (θ or T): The degree of hotness or coldness of a body. It determines the direction of heat flow. Its S.I. unit is the Kelvin (K), but we often use degrees Celsius (°C) in calculations involving temperature *change*. Specific Heat Capacity (c): This is the quantity of heat energy required to raise the temperature of a unit mass (1 kg) of a substance by one degree (1 K or 1 °C). Formula: `c = Q / (m * Δθ)` Rearranging gives the more common form: `Q = m * c * Δθ` Where: `Q` = Heat energy supplied or removed (in Joules, J) `m` = mass of the substance (in kilograms, kg) `c` = specific heat capacity of the substance (in Joules per kilogram per Kelvin, J/kgK or J/kg°C) `Δθ` = change in temperature (in Kelvin, K or degrees Celsius, °C). `Δθ = θ_final - θ_initial` Example: Water has a very high specific heat capacity of approximately 4200 J/kg°C. This means it takes 4200 Joules of energy to heat 1 kg of water by just 1°C. Metals like copper have a low specific heat capacity (around 390 J/kg°C), so they heat up and cool down very quickly. B. The Principle of Method of Mixtures

This experiment is based on a fundamental principle of energy conservation. When a hot object is mixed with a cold object in an insulated container, and no heat is lost to the surroundings:

> Heat energy lost by the hot object = Heat energy gained by the cold object(s)

This is the core principle we will use for our calculations. C. Experimental Procedure: Determining the Specific Heat Capacity of a Solid

Evaluation guide

• Describe how to d etermine the specific heat capacity of a solid using a liquid of a known
• conceptual
• understanding
• Physics