Making a salt and measuring percentage yield

If a solution of two salts is allowed to crystallize we may find that the two salts crystallize out as separate crystals. In some cases both salts crystallize together to form one crystal. This crystal contains the two salts in fixed proportions and is known as a double salt. Ammonium sulfate and iron(II) sulfate are such a pair of salts. The double salt which forms is known as ammonium iron(II) sulfate or Mohr's salt.

In this experiment we shall prepare a sample of Mohr's salt and measure its percentage yield.

Theory of preparation

Watch the video and then use the data to calculate the percentage yield. Why do you think the yield is far less than 100%? You can check your answers here.