What does percent yield mean in chemistry?
Percent yield is the ratio of the actual yield to the theoretical yield. (If it is over 100% it means something went wrong.)
The actual yield is a product that is obtained by experimentation.
The theoretical yield is obtained through stoichiometric calculation.
If the two yields are equal, you have 100 % yield.
Usually you obtain less than 100 %.
It is impossible to obtain a yield greater than 100%.
If that happens, some experimental error must have occurred in the creation of the desired product, actual yield.