Question

Starting with 1.56 g of salicylic acid, a student prepares 1.75 g of aspirin. If the calculated mass of aspirin is 1.88 g, what is the percent yield?

Answer 1

`"% yield" = 93.1%`

Explanation:

In simple terms, a reaction's percent yield tells you how much product you actually produce compared with how much product you could theoretically produce.

`color(blue)(|bar(ul(color(white)(a/a)"% yield" = "what you actually produce"/"what you could theoretically produce" xx 100color(white)(a/a)|)))`

The theoretical amount of product is called theoretical yield and can be calculated by using the assumption that all the molecules of reactants that react produce molecules of product.

The actual amount of product is called actual yield and is measure experimentally by performing the reaction.

In your case, the reaction had a theoretical yield of `"1.88 g"`. This means that if you start with `"1.56 g"` of salicylic acid, you can produce a maximum of `"1.88 g"` of aspirin.

After you perform the reaction, you find that only `"1.75 g"` of aspirin were produced. This is the actual yield of the reaction.

You can thus say that the reaction had a percent yield of

`"% yield" = (1.75 color(red)(cancel(color(black)("g"))))/(1.88color(red)(cancel(color(black)("g")))) xx 100 = color(green)(|bar(ul(color(white)(a/a)color(black)(93.1%)color(white)(a/a)|)))`

The answer is rounded to three sig figs.