Specific Heat Capacity | Matter | Physics | FuseSchool

Key Concepts:

• Heat vs. Temperature
• Heat Capacity
• Specific Heat Capacity
• Energy Transfer (Heat Energy)
• Temperature Change

1. Heat vs. Temperature:

• Temperature: A measure of how hot or cold an object is, measured in degrees Celsius (°C).
• Heat: A form of energy, measured in joules (J).
• Relationship: The more heat transferred to an object, the more its temperature rises. They are related but distinct concepts.

2. Heat Capacity:

• Definition: The amount of heat required to raise the temperature of a material by one degree Celsius.

3. Specific Heat Capacity:

• Definition: The amount of heat required to raise the temperature of one kilogram (1 kg) of a material by one degree Celsius (°C).
• Different materials have different specific heat capacities.

4. Calculating Specific Heat Capacity:

• Equation: Energy Transferred (Q) = Mass (m) × Specific Heat Capacity (c) × Temperature Change (ΔT)
  • Symbolically: Q = mcΔT
• Rearranging the equation to solve for specific heat capacity (c): c = Q / (mΔT)
• Temperature Change (ΔT): New Temperature - Old Temperature

5. Example Problem 1: Calculating Specific Heat Capacity of Lead:

• Given:
  • Energy Transferred (Q) = 128 J
  • Mass (m) = 0.1 kg
  • Old Temperature = 20°C
  • New Temperature = 30°C
  • Temperature Change (ΔT) = 30°C - 20°C = 10°C
• Calculation:
  • c = 128 J / (0.1 kg × 10°C) = 128 J/kg°C
• Result: The specific heat capacity of lead is 128 joules per kilogram Celsius (J/kg°C).

6. Example Problem 2: Calculating Energy Transferred to an LED:

• Given:
  • Mass (m) = 0.005 kg
  • Specific Heat Capacity (c) = 140 J/kg°C
  • Old Temperature = 25°C
  • New Temperature = 5°C
  • Temperature Change (ΔT) = 5°C - 25°C = -20°C
• Calculation:
  • Q = 0.005 kg × 140 J/kg°C × -20°C = -14 J
• Result: The energy transferred to the LED is -14 joules (J). The negative sign indicates that energy is being released (cooling).

7. Significance of Negative Energy Transfer:

• A negative value for energy transferred (Q) indicates that the object is being cooled.
• A positive value for energy transferred (Q) indicates that the object is being heated.
• The temperature change (ΔT) will always be negative if an object is being cooled and positive if it is being heated.

8. Conclusion:

• Specific heat capacity is a crucial property that determines how much energy is required to change the temperature of a substance.
• The equation Q = mcΔT allows us to calculate the energy needed to heat up or cool down a substance to a desired temperature.