Effects of Heat on a Substance

Effects of the Addition of Heat to a Substance:

When objects are subjected to heat, the noticeable changes include:

1. Expansion: When substances are subjected to heat, they increase in length, area, and volume and this is known as expansion. This is due to the fact that the particles of the substance gain more kinetic energyEnergy is the ability to do work. Energy exists in several forms such as heat, kinetic or mechanical energy, light, potential energy, and electrical energy. Units of Energy: The SI unit... More, vibrate stronger than before, break away from the intermolecular force of attraction, and move further apart.

2. Chemical Change: When matter is subjected to heat, it changes form. There may be changes in the chemical properties of a body.

3. Change of State: Substances change from solid to liquid and from liquid to gas as a result of heat.

4. Thermionic Emission: When metals are heated, electrons are emitted from the surface and this occurs at a certain temperature in a process known as thermal emission.

5. Physical Properties: Changes occur when substances are heated. This includes changes in the electrical resistance, magnetic properties, elasticity, conductivity, densityDensity is the measurement of how tightly a material is packed together i.e. how closely the particles are packed in the material. The tighter the material is packed the more its... More and colour.

6. Increase in Temperature: The temperature of bodies increases as a result of heat. The kinetic energy of the body increases which causes the temperature of the substance to increase.

7. Increase in Pressure: As the temperature of gas increases, the pressure increases.

Effects of Removal of Heat from a Substance:

When heat is removed from a substance, the opposite effects of heat added to a substance, as discussed above, will take place. These include

1. Decrease in Temperature of the Substance: When heat is removed from a substance, the average kinetic energy of the substance is reduced. This reduction in the average kinetic energy causes the temperature of the substance to decrease.

2. Contraction of the Substance: When heat is removed from a substance, the average kinetic energy of the particles of the substance is reduced, which in turn reduces the ability of the particles of the substance to move further apart. This causes the substance to contract.