18 what is the percent yield of a reaction, and how is it calculated?

The percent yield is the following equation:

% yield = [(actual yield)/(theoretical yield)] *100

It relates the yield of a chemical reaction, when you expect to obtain in the lab, and what you obtain when you are making the reaction for real.

Actual yield is always a smaller value than theoretical yield, that's because in the lab you always lose some part of the reactants or the product. But sometimes this value can increase even more of the theoretical value, and that happens when there are impurities on the obtained product.

Explanation:

For calculated the percent yield, you have to know the value "actual yield", this is an experimental value, or is given in the problem you want to solve,

almost always exercises say things like "in the lab was founded... ", or "was measure... "

For the theoretical yield, you have to make a calculation, of stochiometric with the data that exercise gives you, remember to follow these steps to solve this theoretical yield:

1. Propose the chemical equation.

2. Find the limiting reactant.

3. Use the limiting reactant and the chemical equation to calculate al the moles of the products obtained.

4. The moles of the product can be transformed in grams.

5. Use the yield equation, remember all the terms of the equation has to be in the same units, it means all in mol or all in grams, as you want. but the same units for all actual yield, and theoretical yield as well.