Definitions [3]
Define rusting?
Rusting: Slow conversion of iron into its hydrated oxide in the presence of moisture and air is called rusting.
Define the following:
Respiration
Respiration: Respiration is a chemical process that takes place in all living beings (slow in plants). In this process, oxygen present in inhaled air reacts with the digested food material in the body. This results in the release of energy, carbon dioxide, and water.
Sugar + Oxygen → CO2 + Water + Energy.
Definition: Anomalous behaviour of water
The behaviour of water between its temperature from 0 °C to 4 °C is called anomalous behaviour of water.
Key Points
Key Points: Anomalous behaviour of water
- Anomalous behaviour of water refers to its contraction when heated from 0°C to 4°C, unlike most liquids that expand on heating.
- At 4°C, water attains its minimum volume and hence its maximum density.
- This behaviour is studied using Hope’s apparatus, in which temperature changes at the upper (T₂) and lower (T₁) parts of the water are recorded over time.
- As cooling begins, denser water at 4°C sinks, causing T₁ to fall rapidly, while T₂ falls more slowly.
- Once water cools below 4°C, its density decreases, causing it to rise, which in turn makes T₂ drop faster, while T₁ remains stable at 4°C briefly before decreasing.
