Electromotive force

[Katie Clark 3B]

Can someone explain what the electromotive force is? And what is its relation to the maximum potential difference?

[Chem_Mod]

Electromotive force is basically the electrical potential that a system has. More potential means the easier it is for the current to flow. It is very similar to Gibbs Free Energy. They both tell you the spontaneity of a reaction. So if we have a positive electromotive force (+E), that means the system has electrical potential and can turn chemical energy into electrical energy. This means the reaction is spontaneous because it can occur by itself with no outside input. So if we have a negative electromotive force (-E), that means the system cannot run by itself and it is non-spontaneous. Let me give you an example, a 9V battery has electrical potential in it (+E). This means that if you plug the battery in, it produces electrical energy. But a dead battery does not have any electrical potential. We can figure out how much work a system does based on the EMF. This is the amount of work the system can do based on its electrical potential. So like how much energy the battery can output based on its EMF. Hope this makes sense!