Answer: 1.57g and 70.5%
Step-by-step explanation:
Theoretical Yield
The theoretical yield of a reaction is the absolute maximum amount of product that could be created with the amounts of reactants.
This problem gives us the amount of hydrochloric acid, which is 6.37 grams. The molar mass of HCl is the molar mass of hydrogen plus the molar mass of chlorine, which is 36.46 g/mol.
To find the moles of HCl, we just divide the mass by the molar mass.
6.37/36.46 = 0.175 moles HCl
Since oxygen is in excess, the amount used in the reaction will be dictated by the amount of HCl used in the reaction. It does not need to be taken into consideration when determining the amount of reactant since it is in excess.
To find the theoretical yield of water, we will do stoichiometry.
Balancing the equation
Written out with the chemical symbols, this equation is
HCl + O2 ⇒H2O + Cl
This is not balanced, since there is 1 hydrogen on the left side and 2 on the right, and 2 oxygens on the left and 1 on the right.
To balance this, we can put coefficients in front of some reactants and products to make sure there are equal amounts of everything on each side.
The balanced equation will be 4HCl + O2 ⇒ 2H2O + Cl
Now, there are 4 hydrogens on the left and 4 on the right, as well as 2 oxygens on the left and 2 on the right. It is balanced.
We can see by looking at the coefficients of the balanced equation that every 4 moles of HCl consumed will produce 2 mole of H2O, so the ratio is 1:2.
To do stoichiometry, we will multiply the moles of HCl by the ratio of H2O to HCl, which is just dividing by 2.
The theoretical yield of water is then 0.175 moles HCl *
= 0.1874 moles H2O.
Our theoretical yield is 0.0874 moles H2O. But the question and the actual yield are in grams, so we will convert this to grams. To convert moles to grams, just multiply the moles by the molar mass. The molar mass of water is 18.0 g/mol, so
0.0874*18.0 = 1.57 g
The theoretical yield is 1.57 g H2O
Percent Yield
Percent yield is much easier. Percent yield is
((actual yield)/(theoretical yield))*100
In this case, our actual yield is 1.11 grams and our theoretical yield is 3.15 grams, so
70.5%
70.5% is the percent yield.