KEY POINTS:
- Every type of substance (element, compound, mixture) possesses a certain amount of energy. This is sometimes referred to as internal energy.
- As chemical reactions involve a change of substances, they are all accompanied by a change in energy.
- Some reactions release energy to their surroundings, other take energy in from their surroundings.
- You may have been previously told that chemical reactions cannot be reversed. However, if you reverse the energy flow, there is a actually good chance you might be able to reverse the chemical reaction.
- For example – sodium reacts with chlorine instantly to form sodium chloride. But if you take sodium chloride, melt it and allow lots of electricity to flow through it, you can obtain sodium and chlorine as elements again. (This is electrolysis – more on this in section 4).
- Reversible reactions are very common. There is only one set of conditions under which a reaction CANNOT be reversed.
THINK OUTSIDE THE BOX:
- What is the difference between an energy type and an energy resource?
- What does it mean when bands like Coldplay say their tours will be ‘carbon neutral’?