States of matter

Three states of matter

Now we will discuss the three states of matter : solid, liquid and gas.

Properties of solid:

·         Fixed shape and volume

·         Have high density

·         Do no flow

·         Certain solid can be compressed but not much, eg rubber

Properties of liquid:

·         Have fixed volume but don’t have a ffixed shape

·         They have less density than solid

·         Flow easily

·         Cannot be compressed

Properties of gases:

·         Have no fixed shape or volume

·         Have very low density

·         Flow easily

·         Can be compressed easily

Comparing the properties of solid, liquid and gases

Shape: either it is a book, chair or table every solid have a fixed shape, their shape remains the same wherever we place it. But in case of liquid and gases they do not have a fixed shape because they change their shape according to the container in which they are stored

Volume: solid and liquid have fixed volume, that means that they will occupy a certain required space, a iron ball of volume 100cubic cm when melted and moulded in another shape will still occupy the same space, similarly when 1l of water when kept in a jar or in a tub may change its shape but in both cases it will occupy same 1l of space. In case of gases the gas can be compressed in a small space by applying pressure, LPG and CNG is an example of large amount of gas compressed in small cylinders.

Density: density of solid is maximum, liquid has comparatively less density and gases have even more density. This difference in density is due to gap in molecules of atoms, the atomic gap in case of solid is negligible. They are very closely packed and hence the density is high, the molecules of liquid are comparatively far with each other and gases are even farther so the density of liquid are less and gases even more less.

Flow: the flow of solid is zero, this means that solid cannot flow, this is because they have a defined shape, their molecules are compact without any gap between them, they have high force of attraction among their molecules which keep them from flowing. But in case of liquid and gases they have a defined shape, their molecules are less compact means they are a bit far and the force of attraction between their molecules are less so they can easily flow. Due to these factors gases can flow even more easily when compared to liquids.

Compression: there are a few solids like rubber and sponge that can be compressed under pressure, rubber is elastic in nature so it can change its shape when force is applied, on the other hand sponge has minute pores from which air gets squeezed out when we press it thus changing its shape. Liquid cannot be compressed although it has space between its molecules, gases have lots of space between them so when compressed  they gets squeezed and decrease in volume.

Why salt, elastic and sponge are called solid?

Although when placed in a container salt and sugar take their shape but the single particle of salt have its definite shape which cannot be changed.

Rubber is elastic in nature so it can change its shape when force is applied on it

Sponge has minute pores from which air gets squeezed out when we press it thus changing its shape.