When a substance is heated, it gains kinetic energy. This means the particles in the gas/liquid move around quicker and in solids they vibrate more.
This is what makes them boil and melt.
Heat is measured on an absolute scale, this means it cannot go below zero because there is a limit to how slow particles can move/vibrate.
Unit of heat energy is joules (J)
The heat travels from hot to cold.
1 of 5
Temperature
Temperature is a measure of the average kinetic energy of the particles in a substance. The hotter something is, the higher the temperature and therefore the higher Kinetic energy of its particles.
Not absolute scales as they can go below zero.
If there's a difference between two objects temperature, energy will flow between them.
The greater the difference in temperature, the faster the rate of cooling.
2 of 5
Specific heat capacity
How much energy stuff can store in a given amount.
Some materials take more energy to heat up than others.
How much energy needed to raise 1kg of a substance by 1'C.
For example, water, its SHC is high, once it's heated it can store lots of energy which makes it good for central heating.
EQUATION: Energy= Mass x SHC X Temperature change
3 of 5
Intermolecular Bonds
You need to put energy in to break intermolecular bonds.
When you heat a liquid, the particles move faster. Eventually when enough of the particles have enough energy to break the attraction to each other, bug bubbles of gas form in the liquid (boiling).
Similar in solids - Heat them enough and eventually the particles break up and it melts.
When a substance is melting or boiling it is using the input energy for breaking the bonds instead of raising the temperature. So you get flat points on the graphs.
When a substance is condensing or freezing, bonds are forming between particles which releases energy. Temperature doesn't go down until all the substance has been turned into a solid or liquid.
4 of 5
Specific Latent Heat
The amount of energy needed to change the state of a substance.
The specific latent heat of melting is the amount of energy needed to melt 1kg of a substance without changing its temperature (material has to be at its melting point already)
The specific latent heat of boiling is the amount of energy needed to boil 1kg of a substance without changing its temperature (material has to be at its boiling point already)
Different for all materials and different for melting and boiling.
Comments
No comments have yet been made