18.0.0: HEAT ENERGY

18.0.0: HEAT ENERGY:

18.1.0:   HEAT ENERGY:
Heat energy is a form of energy that flow from a region of high temperature to a region of low         temperature OR it is a form of energy that is transfer from one point to another due to temperature difference between the two points. Heat can also be defined as a measure of the average kinetic energy of the particles or molecules that make up the substance. Heat is a vector quantity. Its s.i. unit is Joule.

18.2.0:   TEMPERATURE:
Temperature is the degree of hotness or coldness of a substance. It can also be defined as a measure of the average kinetic energy of the particles or molecules that make up the substance. It is a scalar quantity. Its s.i.unit is kelvin

18.3.0:   DIFFERENCE BETWEEN HEAT ENERGY AND TEMPERATURE

              HEAT ENERGY                                                     TEMPERATURE

• Heat is transferred due to temperatur.              Temperature is the degree of       difference.                                                                 hotness or coldness of a
• Heat is a measure of the average internal         Temperature is a measure of the    energy of the molecules of the substance .        average kinetic energy of the                                                                                              molecules of the substance
• It is a scalar quantity                                              It is a vector quantity. 
• its s.i.unit is Joule.                                                    It is s.i. unit is kelvin
• it is represented with letter Q                               it is represented with symbol θ

18.4.0:   SIMILARITIES BETWEEN HEAT ENERGY AND TEMPERATURE

• Heat energy and temperature are physical quantities in physics.
• Heat energy and temperature have their units of measurement
• Heat energy and temperature can be calculated using appropriate formulae
• Heat energy and temperature can be measured/ determined using appropriate instruments
• Heat energy and temperature are properties of phenomenons

18.5.0:   USING MOLECULAR KINETIC THEORY TO EXPLAIN TEMPERATURE
According to molecular kinetic theory of matter:
        matter is made up particles.
        particles are in a state of constant random motion
       the particles possess kinetic energy, and so on
Explanation:
when a substance is heated, the kinetic energy of the molecules or particles that make up the substance is increased and the particle rate of motion is increased. this increased in the average kinetic energy of the particles is the temperature rise of the substance.

18.6.0:   EFFECT OF HEAT ON A SUBSTANCE
When heat energy is added to a substance or removed from the substance, it have an effect on the substance which will be discussed below.
The effect of heat energy on a substance are as follow:
18.6.1:   Effect of addition of heat to a substance:

• increase in the temperature of the substance:                                                                               When is added to a substance, the average kinetic energy of the particles of the substance is increased.  the increase in the kinetic energy of the particles of the substance causes the temperature of the substance to increase.
• Expansion of the substance:                                                                                                        when a substance is heated, the particles of the substance gain more kinetic energy, vibrate stronger than before, brake away from the inter-molecular force of attraction and move further apart. this causes the substance to expand.
• change of state of substance or melting:                                                                                       when a substance is heated\, the molecule of the substance gained more kinetic energy, vibrate stronger than before and brake away from the inter molecular force of attraction that hold the molecules together. the substance then change from solid state to liquid state or the substance melt. Heating the substance further will cause the substance to change from liquid state to gaseous state. 
• vaporization of the substance:                                                                                                       when a substance that is the liquid state is heated, the molecule of the substance gained more kinetic energy vibrate stronger than before and brake away from the inter molecular force of attraction in the liquid that hold the molecules together. the substance then change from the liquid state to vapor

18.6.2:   Effect of removal of heat from a substance:
when heat is removed from a substance, the opposite effects that happened when heat was added to the substance will take place as explained below:

• decrease in the 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 of causes the temperature of the substance to reduced.

• 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 reduced the ability of the particles of the substance to move further apart.this  therefore caused the substance to contract.

KINETIC MOLECULAR THEORY:

according to kinetic molecular theory, matters are made up of particles. The particles process kinetic energy and are in a state of constant random motion

USING KINETIC MOLECULAR THEORY TO EXPLAIN EXPANSION:

When a substance is heated, the molecules of the substance gain more kinetic energy, vibrate strongly and brake away from the intermolecular force of attraction that hold the molecules together and move further apart. This further movement of molecules make the object to expand.

USING KINETIC MOLECULAR THEORY TO EXPLAIN MELTING:
When a substance is heated, the molecules of the substance gain more kinetic energy, vibrate strongly and brake away from the intermolecular force of attraction that hold the molecules together and move further apart. This then cause the substance to melt or change from solid state to liquid estate.

USING KINETIC MOLECULAR THEORY TO EXPLAIN EVAPORATION:
When a substance is heated, the molecules of the liquid gain more kinetic energy, vibrate strongly and brake away from the intermolecular force of attraction that hold the molecules together, move further apart and change to vapour.