Difference Between Heat & Temperature (HL IB Chemistry)

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

The effects of boiling water can be quite different depending on the quantity of water involved!

• 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
• We say that 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 and isolated

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

Open systems are the most common for chemical reactions

• Most chemical reactions take place in open systems in which energy and matter can be exchanged with the surroundings 
• In a closed system, energy can be exchanged with the surroundings but matter cannot
• Although energy can be exchanged between open and closed systems and the surroundings, the total energy of the process cannot change
• This is known as the Law of Conservation of Energy and is a cornerstone to understanding how chemical changes affect the energy flow in and out of systems
• An isolated system cannot exchange matter or energy with the surrounding and are rare