You mix 12 (g) H2 and 7.0 (g) of O2 to form H2O. What is the theoretical yield of the reaction

15.75g of H2O

Explanation:

Equation for reaction

2H2 + O2 - > 2H2O

From the equation, 2 moles of H2 react with 1 mole of O2 to produce 2 moles of H2O

Mole ratio of reactants is 2:1

1 mole of H2 contains 2g

x moles of H2 contains 12g

x = (12*1) / 2 = 6

Therefore, 6 moles of H2 contains 12 g

1 mole of O2 contains 16g

x moles of O2 contains 7g

x = (1*7) / 16

x=7/16=0.4375

Therefore, 0.4375 moles of O2 contains 7g

In solving for theoretical yield,

Firstly, determine the limiting reactant between all reactants involved in the reaction.

Considering the reactants in the reaction above, H2 and O2.

Mole ratio is 2:1

2 moles of H2 is needed to react with 1 mole of O2.

Then, 6 moles of H2 will react with x moles of O2

x = (6*1) / 2=3

Therefore, 6 moles of H2 will react with 3 moles of O2

1 mole of O2 reacts with 2 moles of H2.

Then, 0.4375 mole of O2 will react with (0.4375*2) = 0.875 moles of H2

But we are given 7g~0.4375 moles of O2 and, 12g~6 moles of H2.

From the stoichiometry, 6 moles of H2 needs 3 moles of O2.

But only 0.4375 moles of O2 is made available in the reaction.

Hence, O2 is the limiting reactant

Now, with the limiting reactant being O2, we can find the theoretical yield of the product.

Stoichiometric ratio between the limiting reactant and the product is

1:2

This means, 1 moles of O2 reacts to produce 2 moles of H2O

0.4375 moles of O2 will produce x moles of H2O

x = (2*0.4375) / 1=0.875 moles.

Therefore, the theoretical yield of the product is 0.875 moles of H2O

or 15.75g of H2O