🧊 6. Maximum Density at 4°C

🧪 Density of Water

• Water is densest at 4°C.
• When cooled below 4°C, it expands slightly due to hydrogen bonds.

❄️ What Happens at 0°C?

• Water freezes and becomes ice.
• Ice is less dense, so it floats on water.

🧠 Mnemonic:
“Cool Water Floats” → Cool = Cold → Ice Floats

🐟 Importance for Aquatic Life:

• Ice floats and forms a layer on top of lakes or rivers.
• This layer insulates the water below and keeps it from freezing.
• Fish and other organisms can survive underneath, even in freezing temperatures.

🧊 So, ice on top = blanket for aquatic life!

✅ Summary Chart

Property	Water’s Behavior	Why It’s Important
High Specific Heat	Heats/cools slowly	Keeps body/environment stable
High Heat of Vaporization	Absorbs a lot of heat before evaporating	Helps in cooling (sweat, transpiration)
Cohesion	Water sticks to itself	Helps plants pull water upward
Surface Tension	Water surface acts like a skin	Insects can walk on water
Ionization	Forms H⁺ and OH⁻	Helps in chemical reactions and pH balance
Max Density at 4°C	Ice is less dense than water	Ice floats and insulates aquatic life