1. What Is Specific Heat Capacity?
Specific heat capacity tells how much heat a material needs to change its temperature. Some materials heat up quickly, while others take time. This difference is captured by their specific heat capacity.
In simple words, it is a measure of how much energy each kilogram of a substance needs to increase its temperature by 1°C (or 1 K).
2. Formal Definition
Specific heat capacity of a substance is the amount of heat required to raise the temperature of 1 kg of the substance by 1°C (or 1 K).
\( Q = mc\Delta T \)
Here, c is the specific heat capacity.
3. Understanding the Formula
The heat needed to change temperature depends on three factors: the mass of the substance, the specific heat capacity, and the temperature change. The formula connects all of them.
3.1. Meaning of Symbols
- Q → Heat supplied or removed (joules)
- m → Mass of the substance (kg)
- c → Specific heat capacity
- ΔT → Temperature change (°C or K)
3.2. Why ΔT Can Be in °C or K
Temperature differences are the same on both scales, so ΔT is identical whether measured in Celsius or Kelvin.
4. Why Different Materials Heat Up Differently
The value of specific heat capacity depends on how particles in a substance store energy. Materials with strong internal bonding or more ways to store energy need more heat to warm up.
This is why some objects feel hot quickly while others stay cool for longer.
4.1. Low Specific Heat Capacity
Materials with low c heat up and cool down quickly because they need little energy to change temperature.
Examples: metals like copper and iron.
4.2. High Specific Heat Capacity
Materials with high c heat up slowly and cool down slowly. They absorb or release a lot of heat without large temperature changes.
Examples: water, wood.
5. Specific Heat of Water
Water has an unusually high specific heat capacity. This is why it takes a long time to heat water and also why water stays warm for longer. This property has major effects on climate and temperature regulation in nature.
5.1. High Heat Storage
The high value of c for water helps moderate temperature changes in oceans, lakes, and even inside the human body.
5.2. Practical Impact
- Coastal areas have milder temperatures.
- Hot water bottles stay warm for long periods.
- Large bodies of water heat and cool slowly.
6. Heat Capacity vs Specific Heat Capacity
Heat capacity and specific heat capacity are related but not the same. It is important to distinguish between the two.
6.1. Heat Capacity
Heat capacity is the amount of heat needed to raise the temperature of an entire object by 1°C.
\( C = \dfrac{Q}{\Delta T} \)
6.2. Specific Heat Capacity
Specific heat capacity refers to the heat required per kilogram of material. It allows fair comparison between different substances.
7. Everyday Examples
- A metal spoon heats up quickly on a stove because metals have low specific heat.
- Water takes time to boil because it has high specific heat capacity.
- Land gets hotter faster than the sea during the day and cools down faster at night because of the difference in specific heat.