Specific Heat Capacity

Specific heat capacity is the amount of heat required to increase the temperature of 1 unit mass of a substance by 1°C. It is represented by the symbol ‘c’.

• SI Unit: Joule/(kg°C)
• CGS Unit: cal/(g°C)

The amount of heat required to raise the temperature of an object depends on:

1. Mass (m): Heavier objects require more heat.
2. Specific Heat (c): Different materials need different amounts of heat.
3. Temperature Change (ΔT): The greater the temperature increase, the more heat is required.

Formula for Heat (Q);

The heat energy (Q) needed to raise the temperature of an object is given by:

Q = m × c × ∆T

Q = m × c × (T_f − T_i)

Where,

• Q: Heat energy (in Joules or calories)
• m: Mass of the object (in kg or g)
• c: Specific heat capacity of the substance
• T_i​: Initial temperature
• T_f​: Final temperature

Key Observations:

• Hydrogen has the highest specific heat (3.42 cal/g°C), meaning it absorbs heat efficiently.
• Water (1.0 cal/g°C) has high specific heat, making it an effective coolant.
• Metals like iron (0.11 cal/g°C), copper (0.09 cal/g°C), and gold (0.03 cal/g°C) have low specific heat, meaning they heat up and cool down quickly.
• Liquids like alcohol (0.58 cal/g°C) and kerosene (0.52 cal/g°C) retain more heat than metals but less than water.

Thus, specific heat varies across different substances, affecting their use in heating, cooling, and industrial applications.

1. Aim: To compare the specific heat capacity of different metals by observing how deeply they melt wax when heated.

2. Requirements

• Tray with thick wax layer
• Three solid spheres (Iron, Copper, and Lead) of equal mass
• Burner or spirit lamp
• Large beaker with boiling water

3. Procedure

• Heat water in a beaker and place the three metal spheres (iron, copper, and lead) in it.
• Keep the spheres in boiling water until they all reach 100°C.
• Quickly remove the spheres from the boiling water and place them on a thick wax layer.
• Observe and note how deep each sphere sinks into the wax.

Specific heat capacity of metals

4. Observation

• Iron sphere sinks deepest into the wax.
• Copper sphere sinks to an intermediate depth.
• Lead sphere sinks the least.

5. Conclusion: The sphere that absorbs more heat from boiling water releases more heat to the wax, melting more wax and sinking deeper.

• Iron has the highest specific heat capacity, as it absorbs and releases more heat.
• Lead has the lowest specific heat capacity, as it absorbs and releases less heat.

This confirms that different materials have different specific heat capacities, affecting how much heat they can store and transfer.