1. suppose 0.7542 g of magnesium reacts with excess oxygen to form magnesium oxide as the only product, what would be the theoretical yield of the product?

2. if 0.8922 g of magnesium oxide is obtained from the reaction indicated in #1 above, what would be the percent yield of the magnesium oxide?

3. suppose the percent yield was calculated to be over 100%, what possible reasons could you give to account for it?

Answer :

(1) The theoretical yield of product, is, 1.257 grams.

(2) The percent yield of is, 64.13 %

(3) If the percent yield is calculated to be over 100% then there might be some impurity present in the desired product.

Solution : Given,

Mass of Mg = 0.7542 g

Molar mass of Mg = 24 g/mole

Molar mass of MgO = 40 g/mole

First we have to calculate the moles of Mg.

Now we have to calculate the moles of

The balanced chemical reaction is,

From the reaction, we conclude that

As, 2 mole of react to give 2 mole of

So, 0.03142 moles of react to give 0.03142 moles of

Now we have to calculate the mass of

Theoretical yield of = 1.257 g

Experimental yield of = 0.8922 g

Now we have to calculate the percent yield of

Therefore, the percent yield of is, 70.97 %

If the percent yield is calculated to be over 100% then the product would be greater than 1.257 g which indicates that there might be some impurity present in the desired product.

lithosphere and asthenosphere