So if you get a value greater than 100%, there are two things you should check.

One, make sure you've done your calculations correctly, and two,

if you've done the actual experiment, to look back through and see if

there's something else in that sample that you're actually weighing along with it.

Such as a wet sample, so you're actually weighing the mass of water and

your product rather than just the product alone.

So let's look at an example with the percent yield.

What is the percent yield if the theoretical yield for a particular set of

conditions is 0.750 grams and the actual yield is 0.606 grams of zinc sulfide.

So we're given the balanced chemical equation.

And we can look at the information given.

We're given the actual yield, which is 0.606 grams.

We're given the theoretical, which is 0.750 grams.

Now I simply need to calculate the percent yield,

which will be equal to 0.606 divided by 0.750, times 100.

And when I do that,

I end up with a percent yield of 80.8%.

This tells me I got 80.8% of what I actually expected to get.

Not a bad return on my reaction.