Change of State- Grade 5

 Effects of heating matter

• Matter - everything around us. All materials and substances that exist and occupy space.

• States of matter - different forms of substances, that is solids, liquids and gases.

• Change of state - to turn from one form to another, for example from solid to liquid. It occurs when matter absorbs or loses energy.

  
  

When solids are heated, they change their states of matter. Some solids such as candle wax and cooking fat, melt into liquid, while ice cubes melt into water (liquid)

The process in which a solid change to a liquid is called melting.

There are some solids that change to gases when heated, for example mothballs. The process in which a solid change directly to a gas is called sublimation.

Heating Liquids.

Some liquids change their state of matter through heating.

Water (liquid) changes to water vapour (gas) when heated. The process in which a liquid boils and changes to a gas is called evaporation.

Effects of cooling matter.

Cooling water vapour

When vapour is cooled it changes to liquids. This means that it has changed its state from gaseous state to liquid state.

The process in which a gas changes to a liquid is called condensation.

Cooling Liquids

When liquids such as water, melted fat and melted candle wax are cooled, they harden and become solids. ● They change from liquid state to solid state. The process in which a liquid change to a solid is called freezing.

When gases such as mothball vapour are cooled, they become solids without forming liquids first. A mothball is

made up of a substance known as naphthalene whose vapour changes from gaseous state to solid state on cooling.

The process in which a gas changes directly to a solid without going through the liquid state is known as deposition.

Application of change of state of matter.

●   Heating is used to dry grains, fish and other foods to preserve them. It also dries clothes and salt through evaporation.

●   Heating of water bodies causes evaporation and cooling of air forms rain through condensation.

●   Cooling preserves food and also makes ice through freezing. Solid metal melts into liquid on heating.

Water cycle

Change of State

A cycle is something that happens over and over again. It has no beginning and no end. The following are the water cycle stages:

Stage 1: Evaporation and Transpiration.

 The water cycle begins with the sun heating the water bodies. As the water heats up, it evaporates.

In addition, green plants also release water vapour into the

air in a process called transpiration. The vapour rises up into the sky.

Stage 2: condensation

High up in the sky, the temperatures are cool. Water vapour in the clouds cool down and becomes liquid water. This liquid water is stored in clouds. The process of water vapour turning back into liquid is called condensation.

Stage 3: Precipitation

The water falls from the sky in the form of rain, snow or hail through precipitation.

Stage 4: Runoff and infiltration

As the water fall on the ground, the water forms streams and rivers and collects in lakes and oceans. This is known as run-off. Besides runoff, water is also absorbed into the soil. This is called infiltration. The water get stored as groundwater. The cycle then continues.

Project: Making candles