Lesson 4: Thermal Properties of Water

🔥 1. Heat Capacity of Water

👉 What is Specific Heat Capacity?

• Definition: It is the amount of heat (energy) needed to raise the temperature of 1 gram of a substance by 1°C, usually from 15°C to 16°C.
• For water, this value is 4.184 Joules per gram per degree Celsius (J/g°C).

🔍 Why Is It Important?

Water can absorb or release a large amount of heat without changing its temperature much. This helps to keep our body temperature and the environment stable.

🧠 Mnemonic to Remember:
“Water is a Heat Saver”
W – Water
H – High
S – Specific heat
→ So water saves us from sudden temperature changes.

💡 Real-Life Analogy:

Imagine a metal spoon and a bowl of water placed in the sun.

• The spoon gets hot quickly.
• The water stays cool longer.
  This is because metal has low specific heat, and water has high specific heat—it resists quick temperature changes.

🧪 How Does Water Do This?

Water has hydrogen bonds between its molecules.
When water heats up, most of the energy goes into breaking these bonds—not increasing temperature.
So, water heats up slowly and also cools down slowly.