P1 - Moving and Storing Heat

Heat;

• a measure of energy
• unit = joules (J)

Temperature;

• a measure of hotness
• measured in degrees celsius, or Fahrenheit

What is an absolute scale?

It is a scale that cannot go below zero.

An example of an absolute scale is heat.

Temperature is not an absolute scale, because it can go below zero.

When things are heated, what do the particles gain?

They gain kinetic energy, which makes them vibrate faster or move around faster.

It depends on the state of the substance as to how kinetic energy affects it.

See the following pages for more information.

Heat, when increased, makes the particles within a substance gain more kinetic energy. It affects a substance differently depending on its state.

For solids...

• vibrate more rapidly
• hit against each other

For liquids and gases...

• move around faster

Temperature is a measure of the average kinetic energy the particles in a substance have.

It relates to heat because the hotter something is, the higher its temperature and average kinetic energy.

The energy in these particles can flow from a hotter object to a cooler object.

For example, a cup of hot coffee will lose energy to its surroundings.

The rate of the energy being lost depends on the difference between the heat.

For example, a coffee in a hot room would lose energy slower than in a cold room.

Some materials need more heat energy to raise the temperature than other materials.

For example, water requires more energy to heat than mercury.

Materials store energy as they heat up, and release it as they cool down.

Specific heat capacity (SHC) is a measure of the amount of energy a substance can store. More importantly, it is a measure of how much energy is needed to raise 1kg of a substance by 1 degree celsius.

You need to learn this equation:

ENERGY = MASS x SPECIFIC HEAT CAPACITY x TEMPERATURE CHANGE

This is all you need to know about moving and storing heat for your exam. Try practising some questions on SHC before the exam.