Short Answer

Specific heat is the amount of heat energy required to raise the temperature of 1 kilogram of a substance by 1°C (or 1 K). It depends on the nature of the substance and indicates how much energy is needed to increase particle motion.

For example, water has a high specific heat (4186 J/kg·°C), meaning it requires more heat to raise its temperature than metals like iron. Specific heat is important in calculations involving heat transfer and energy changes in substances.

Detailed Explanation

Specific Heat

Specific heat, also called specific heat capacity, is a measure of a substance’s ability to absorb or release heat for a given temperature change. It is an intensive property, meaning it does not depend on the amount of substance, unlike heat capacity.

The formula for specific heat is:

Where:

•  = specific heat (J/kg·°C or J/kg·K)
•  = heat energy absorbed or released (Joules)
•  = mass of the substance (kg)
•  = temperature change (°C or K)

Specific heat helps in calculating energy requirements for heating or cooling a substance.

1. Relationship with Heat Capacity

• Heat capacity (C): Energy required to raise the temperature of the entire substance by 1°C.
• Specific heat (c): Heat capacity per unit mass.
• Formula:

Example:

• Heating 2 kg of water (c = 4186 J/kg·°C) by 1°C requires:

Thus, specific heat allows calculation based on mass and temperature change.

2. Factors Affecting Specific Heat

1. Nature of Substance:
   • Substances with strong intermolecular forces or many degrees of freedom (like water) have high specific heat.
   • Metals with closely packed atoms have lower specific heat.
2. Phase of Substance:
   • Solids, liquids, and gases have different specific heats.
   • For example, ice has lower specific heat than liquid water.
3. Temperature Range:
   • Specific heat can slightly vary with temperature.

3. Examples in Daily Life

• Water as a coolant: High specific heat makes it ideal for cooling engines and radiators.
• Climate moderation: Oceans and lakes absorb heat without large temperature changes.
• Cooking: Metals like iron heat quickly due to low specific heat, while water heats slowly.
• Thermal storage systems: Materials with high specific heat store energy efficiently.

These examples show how specific heat influences energy transfer in natural and artificial systems.

4. Scientific Significance

• Thermodynamics: Specific heat is used in calorimetry to determine energy changes.
• Engineering: Designing heating, cooling, and insulation systems requires knowledge of specific heat.
• Chemistry: Helps calculate enthalpy changes during reactions and phase transitions.

5. Measurement of Specific Heat

• A substance of known mass is heated, and the temperature change is measured.
• Heat supplied is calculated using:
• Solving for  gives:

Example: Heating 500 g of water by 5°C with 10465 J of energy:

Conclusion

Specific heat is the energy required to raise the temperature of 1 kg of a substance by 1°C. It is a key property that determines how substances respond to heat, affects natural phenomena, and is critical in engineering, chemistry, and daily life. Substances with high specific heat absorb more energy for the same temperature change, making water and similar materials important in thermal regulation and energy storage.