little bit...about HEAT

There are few things that we all studied in this chapter.H.E.A.T.

Pressure Law states that for a fixed mass of gas,the pressure of the gas is directly proportional to its absolute temperature when the volume is constant.

Latent Heat is known as the heat absorbed at constant temperature during a change of phase

Latent Heat of Fusion is known as the heat absorbed by a melting solid.

Latent Heat of Vaporisation is known as the heat absorbed during boiling.

Specific Latent Heat is the amount of heat required to change the phase of 1 kg of the substance at a constant temperature

Specific Latent Heat of Fusion is defined as the amount of heat required to change 1 kg of the substance from solid to liquid phase without a change in constant temperature.

Specific Latent Heat of Vaporisation is defined as the amount of heat required to change 1 kg of the substance from liquid to gaseous phase without a change in constant temperature.

Liquid- in-glass Thermometer

Liquid-in-glass Thermometer

LIQUID used should

- be easily seen

- expand and contract rapidly over a

wide range of temperature

- not stick to the glass walls of the the

capillary tube

Mercury is commonly used because

- it is good conductor of heat

- it has a high boiling point

- it expands uniformly when heated

- it is opaque and it can be seen easily

TEMPERATURE SCALE

Two fixed temperature are identified,as a high

and low points of the scale.They

are called fixed temperature,because

it can be reproduced in a laboratory

anywhere in the world.

Ice point,the lower fixed temperature is the

melting pont of pure ice whici is 0 degree celcius.

Steam point,the higher fixed temperature

is the boiling point of pure water which is 100 degree celcius.

SENSITIVITY of a thermometer can be increased with;

- capillary tube with a finer bore

- a smaller tube

- a glass bulb with a thinner wall

thermal equlibrium

Thermal equlibrium is a state in which there is no net flow of heat between two objects

Ok,,there are few things i want to share with you;

THERMAL CONTACT

When a stone is dropped into a beaker of hot water,they come into into thermal contact with each other.

HEAT TRANSFER

As the temperature of water is higher than the stone,the rate of heat transfer from water to stone is greater than the the rate of transfer from stone to water

As a result,there is a net flow of heat from water to stone.Water loses heat and becomes cooler while stone gains heat and becomes hotter.

REACH THERMAL EQULIBRIUM

After some time,the temperature of water is the same with the stone.

However,the transfer of heat still take place but the rate of heat transfer from water to stone and vice versa is the same.

This mean that there is no net flow of heat between them.

Then,the stone and the water are said to be in thermal equlibrium.