Physical Characteristics of Water


5.1  Physical Characteristics of Water


Physical Characteristics of Pure Water

Boiling point = \(100^\circ \text{C}\)

Freezing point = \( 0^\circ \text{C}\)


Density = \(1\text{ g cm}^{-3}\)

Effects of absorption and release of heat on the state of water

1) Heat is absorbed

SOLID \(\begin{aligned} &\text{melting}\\ &\quad\rightarrow \end{aligned}\) LIQUID \(\begin{aligned} &\text{evaporation/boiling}\\ &\quad\rightarrow \end{aligned}\)GAS

SOLID \(\begin{aligned} &\text{sublimation}\\ &\quad\rightarrow \end{aligned}\) GAS

2) Heat is released

GAS \(\begin{aligned} &\text{condensation}\\ &\quad\rightarrow \end{aligned}\) LIQUID \(\begin{aligned} &\text{freezing}\\ &\quad\rightarrow \end{aligned}\) SOLID

GAS \(\begin{aligned} &\text{sublimation}\\ &\quad\rightarrow \end{aligned}\)SOLID

Composition of Water

  • Water is a compound  which is made up of 2 hydrogen atoms and 1 oxygen atom
  • Can determine the composition of elements in a water molecule through electrolysis
  • During electrolysis, oxygen gas produce at anode while hydrogen gas at cathode

Evaporation of Water

What is evaporation?
  • Evaporation of water is the process that happens at the surface of water that changes water to water vapour

Factors affecting the rate of evaporation

  1. Humidity
  2. Surrounding temperature
  3. Exposed surface area of water
  4. Movement of air

Applications of Evaporation of Water in Daily Life

  1. Clothes hung on clothes lines have large exposed surface areas. So, the clother will dry faster
  2. Sea salt is obtained from the evaporation of seawater
  3. Seafood that is dried can be kept longer as microorganisms cannot survive without water