How to calculate percentage yield in a reaction if number of moles are given?Also, how do we know limiting rgt

First of all, find the molar mass of the compound. The formula for Percent Yield is :

(Actual Mass/ Theoretical Yield)100



Quite simple really. Actual mass is the mass of the product found in the laboratory. The theoretical yield is the maximum amount you can recieve from the reaction. To find the theoretical yield, find the lim. reagant. The lim. rgt is the one that runs out first. so if you have a bal. equation like O2+2H2=2H2O, with 3moles of H2 and 5 moles of O2, then the H2 would run out first, lim rgt. use factor label method, using the mole relationship between H2O and H2 (always, always, ALWAYS start with the lim. rgt!) so you would get:



(3mol H2/ 1) * (2mol H2O/ 2mol H2) = 3mol H2O



That is your theoretical yield and if your actual yield found in the lab was 2.405, then you would solve:



(2.405/ 3) * (100)= 80.17% H2



This is your percent yield, the amount with which you used efficiently in the reaction. (shows the efficiency of the reaction)



Hope this helps- Chemistry is always fun when you know what you're doing! LOL! = )How to calculate percentage yield in a reaction if number of moles are given?Also, how do we know limiting rgt
Percent yield is the actual obtained product divided by what you expect to yield based on the balaced chemical equation.



You can just substitute your given moles and find the moles of product or reactant. that you need.



Notice how I said product or reactant......This is the power of that balanced equation. You can tell what you need or what you expect by the equation.



To make things simple......



to make 1 Big Mac = 3 slices of bread + 2 meat patties and some other stuff....so if I give you 8 slices of bread....and you have 20 meat patties.....you have excess meat but bread for only 2 sandwiches.



same with a chemical equation. look at the moles of one reactant and see how much of the other you need. you will be able to determine if you have enough by inspection.