Page 91 - Innovator's Science-8

can make the water level appear to decrease slightly when poured into
another container, but the true volume of the water remains the same.

Overall, liquids fit the shape of their container but keep a steady volume
because their particles can move within a limited space.
Let us now compare interparticle forces of attraction in liquids and solids.
Moving finger through water
Take some water in a shallow vessel and try to move your finger through it.
Are you able to move your finger through the water?

You can move your finger through water without breaking or cutting it
permanently, which cannot be done in the case of solids. When you try this,
Science you are temporarily displacing water. As soon as you remove your finger,
Bytes
the position of the water is restored. We can say that in liquids, the
Testimony
Liquids have weaker interparticle attractions are slightly weaker than in solids, but still strong
interpar cle forces than enough to keep the particles close together.
solids, allowing their
par cles to move and When a liquid is heated, it reaches a special temperature called the boiling
slide past each other point. This is the temperature at which the pressure of the vapour formed
easily. This is why we can
move our finger through by the liquid becomes equal to the atmospheric pressure around it. At this
water but not through a point, the liquid starts to boil and change into a gas or vapour. The particles
solid object. When a in the liquid move very fast and spread far apart, are weakening the forces
liquid is heated, its
par cles move faster. At a that hold them together. This allows the particles to escape from the liquid
certain temperature, and become gas. For example, water boils at 100°C at normal atmospheric
called the boiling point,
the liquid changes into pressure, turning into steam. The boiling point changes with pressure—at
vapour. For water, this higher altitudes where the air pressure is lower, water boils at a
temperature is 100°C at temperature lower than 100°C.
normal atmospheric
pressure. The boiling At the boiling point, the formation of vapour is very fast and occurs not only
point changes with air at the surface but also within the liquid. This process is observed as bubble
pressure at higher
al tudes, water boils at a formation in the liquid. However, vapour formation occurs at all
lower temperature. Even temperatures, even below the boiling point, though slowly and only at the
below the boiling point,
some par cles of a liquid surface. This slower process is known as evaporation .
escape slowly from the
surface to form vapour; GASEOUS STATE
this slow process is When you take two transparent gas jars or glass tumblers and label them A
known as evapora on.
Gases have par cles that and B, then create smoke by burning an incense stick, you can trap the
move freely in all smoke inside Gas Jar A by holding it upside down over the smoke. Then,
direc ons, spreading out
to fill the en re container. turn Gas Jar A over and cover it with a glass plate.
Thus, gases have neither Hold Gas Jar B upside down and gently place it over the glass plate covering
a fixed shape nor a fixed
volume. Gas Jar A. Slowly remove the glass plate while keeping the two jars close
together so no smoke escapes. You will observe the smoke spreading inside

Gas Jar B, filling the entire space. This shows that gases do not have a fixed

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Science-8