So we have plenty of that.

So really we're only worried about how much zinc nitrate do we need?

So, I've got a couple of things going on here.

I've got to figure out how much zinc sulfide do I need to plan on making,

if I know I'm only going to have 85% yield.

And then I need to use stoichiometry to figure out how much zinc nitrate is

going to be needed to make that amount of zinc sulfide.

So let's first look at what we have for the zinc sulfide in that percent yield.

Remember that percent yield equals the actual,

or the experimental amount, over the theoretical, times 100.

So I can use that equation to actually figure out how much I

need to plan on making.

So I know my percent yield is 85%.

My actual yield needs to be 625,

because this is what I actually need to end up with at the end of the experiment,

and what I'm actually solving for here is the theoretical amount.

How much do I need to plan on making so that I end up with 625 grams?

So we know that x is going to be greater than 625.

And when I do the calculation, I'm going to have to solve for that x.