Difference Between Heat & Temperature (DP IB Chemistry): Revision Note

Difference between heat and temperature

What is the difference between heat and temperature?

• This can be illustrated using a beaker of boiling water and a pipette:

Diagram to demonstrate the difference between heat and temperature

• You would get a very nasty burn if a whole beaker of boiling water spilled onto to your hand, but a drop of boiling water would cause little problem

• The water is at the same temperature in the pipette as in the beaker, but the beaker has a much higher heat content

• Temperature is a measure of the average kinetic energy of the particles whereas heat is a measure of the energy content of a substance

• The particles have kinetic energy because they are moving

  • The faster they move the more energy they have and the higher the temperature of the substance

Conservation of energy

• Energy is a measure of the ability to do work

• There are many different types of energy and heat is only one of them

• During chemical reactions energy flows in and out of the reaction vessels:

  • Inside the reaction vessel is known as the system

  • Outside the reaction vessel is known as the surroundings

• Systems come in three types: 

  • Open

  • Closed

  • Isolated

Diagram to show energy and matter transfer in three types of system

• Most chemical reactions happen in open systems, where both matter and energy can move in and out

• In a closed system, energy can move in and out, but matter cannot

• In an isolated system, neither matter nor energy can be exchanged with the surroundings, these are very rare

• Whether the system is open or closed, the total energy stays the same, it just moves between the system and the surroundings

• This idea is called the Law of Conservation of Energy:

  • Energy cannot be created or destroyed, only transferred