Year 12s: what will be the first way you research your future options? >>

how to work out percentage yield

unkownone

How to u find out the % yield of an product from a reaction

Reply 1

Lord_Farquad

Yeild = Begining/100 * ending

Reply 2

cptbigt

unkownone

How to u find out the % yield of an product from a reaction

It would of been probably easier to just put all your questions in the same thread instead of making new one's all the time :tongue:

And yes as stated above:

(Actual Yield/Theoretical Yield) x 100

For even more clarity if you need it:

2Mg + O₂ -> 2MgO

If you used 2g of Mg then you work out the number of moles for this = 2/24 = 0.08 moles

You know its a 1:1 ratio of magnesium to magnesium oxide so you can work out how much you *should* get if you had a 100% yield.

0.08 moles x 40 (molar mass of magnesium oxide) = 3.2g - this is your theoretical yield.

But you only got 2.2g of it after weighing its mass.

So percentage yield would =

(2.2g/3.2g) x 100 = 69% Yield :smile:

Reply 3

R_B_R

but wouldn't the molar mass in this case be 80, since there is two lots of magnesium oxide for the products? :s-smilie:

Reply 4

R_B_R

and also, how do you work the theoretical yield when the ratio is not 1:1?

Reply 5

Nick0110

I guess i'm a bit late, but RBR, in answer to your first question there are double the amount of atoms for each part, i.e Mg+O = MgO is in the Ratio 1:1

2Mg + O2 = 2Mgo is in the Ratio 1:1