Physical Characteristics of Water

5.1

Physical Characteristics of Water

Physical Characteristics of Pure Water

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

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

Colourless

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

Humidity
Surrounding temperature
Exposed surface area of water
Movement of air

Applications of Evaporation of Water in Daily Life

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