Today we're going to talk about reactions and their yield. Now, the amount of product produced when all the reactants are completely used up in other words, when our reaction runs to completion is known as the theoretical yield. Note that most reactions don't actually run to completion and that's because our reactions usually reach equilibrium before any of the reactants are depleted and that means that theoretical yield will not be possible. We'll get a number below theoretical yield and this number is known as the actual yield of our experiment. Now, to see how far a reaction proceeded, in other words, how close it got to our theoretical yield we simply find actual yield and theoretical yield. We divide two.