Class 9 > Unit # 09:Thermal Properties of Matter > Heat Capacity & Specific Heat

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Heat Capacity, Specific Heat Capacity, and Effects of Water's Large Specific Heat

Q.3 Define Heat Capacity and Specific Heat Capacity with formulae and units.

1. Heat Capacity

"The amount of heat required to raise the temperature of a substance through $1^\circ\text{C}$ or $1\text{ K}$ is called Heat Capacity."

Formula

$C = \frac{Q}{\Delta T}$

Where:

• $C$ = Heat Capacity
• $Q$ = Amount of heat supplied
• $\Delta T$ = Change in temperature

Unit

Its SI unit is joule per Kelvin ($\text{J/K}$).

2. Specific Heat Capacity

"The amount of heat required to raise the temperature of $1\text{ kg}$ of a substance through $1^\circ\text{C}$ or $1\text{ K}$ is called Specific Heat Capacity."

Formula

$c = \frac{Q}{m \cdot \Delta T}$

Where:

• $c$ = Specific Heat Capacity
• $m$ = Mass of the substance
• $Q$ = Amount of heat required
• $\Delta T$ = Change in temperature

Unit

Its SI unit is joule per kilogram-Kelvin ($\text{J/kg}\cdot\text{K}$).

Q.4 Write three effects due to large specific heat of water.

We know that water has a remarkably large specific heat ($\approx 4200\text{ J/kg}\cdot\text{K}$). Due to this unique property, it plays a vital role in everyday life and nature:

1. Climate Moderation in Coastal Areas:

   The large volumes of water in oceans and lakes absorb and release huge amounts of thermal energy with minimal temperature change. This helps maintain stable temperature ranges in surrounding coastal regions, preventing extreme weather variations.

2. Use as a Engine Coolant:

   Because of its high specific heat capacity, water can absorb a massive amount of heat with a relatively small rise in temperature. Therefore, water is used with coolants inside vehicle radiators to efficiently prevent engines from overheating.

3. Regulation of Human Body Temperature:

   The human body consists of roughly 60–70% water. Water's high specific heat helps stabilize internal body temperature against external environmental fluctuations, protecting vital metabolic processes.

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