KINETIC MODEL OF MATTER

STATES OF MATTER PROPERTIES OF MATTERS There are three states of matter that is solid liquid and gas. PROPERTIES OF MATTERS SOLID In solid particles are closely packed together. Molecules are arranged in regular pattern Molecules can vibrate to and fro but cannot change the position The force of attraction between the molecules is very strong. Solid has fixed shape and volume It cannot compress

LIQUID Particles are close together but compare to solid particles are little far. The attraction force between the molecules are weak compare to solid. Molecules can freely move from one place to another. Liquid has no fixed shape but has fixed volume. It cannot compress easily

GAS Particles are very far apart. The attraction force between the molecules are very weak Particles can move randomly with higher speed. Gas has no fixed shape and fixed volume. It can compress

EFFECTS OF TEMPERATURE ON MOTION OF MOLECULES When the temperature is increased the molecules gain kinetic energy. The increasing kinetic energy makes molecule moves faster and increase there separation (expand). The gas molecules are in random continuous motion. When the gas molecules are in a container, they exerts a force on a wall of the container when they collide with it. Since the force is exerted over an area, a pressure is produced. If the temperature of the gas increases, the gas molecules gain K.E and moves faster. So the molecules exerts on the wall of the container and pressure also increase. PRESSURE LAW (GAS LAW 2) For fixed mass of a gas at a constant volume, the pressure is directly proportional to the temperature.

EVAPORATION When the liquid below its boiling point changes into gas this process is called evaporation. It happens because some of the particles in the liquid moves faster than others. The faster one near the surface have enough energy to escape and form a gas.

FACTORS AFFECTING EVAPORATION 1. Temperature of the liquid Rate of evaporation increases as the temperature of the liquid increases lower temperature higher temperature

2. Surface area of the liquid Rate of evaporation increases as the surface area of the liquid increases. Small exposed surface Larger exposed surface

2. Drought over the surface of the liquid Rate of evaporation increases when the drought over the liquid increases (wind blows over the surface of the liquid). Still air wind

THE COOLING EFFCT OF EVAPORATION Evaporation has a cooling effect THE COOLING EFFCT OF EVAPORATION Evaporation has a cooling effect. If the high energetic fast moving particles escape from the liquid, slower ones left behind. so the temperature of the liquid is less than before and the liquid cools down. Why we feel cold when wind blows after swimming? Wind helps to carry away water vapour formed by evaporation, thus increasing the rate of evaporation. When the water droplets evaporate, they remove heat from our body and thus, we feel cool.