40.0 grams zinc react with 18.00 grams of hydrochloric acid.

Question

Calculate the theoretical yield of the reaction. If the actual yield is 23.0 grams of zinc chloride, what is the percent yield of the reaction.

Answer 1

First, write the correctly balanced equation:

Zn(s) + 2HCl(aq) ==> ZnCl₂(aq) + H₂(g) ... balanced equation

Next, find the limiting reactant:

For Zn: 40.0 g Zn x 1 mol Zn/65.38 g x 1 mol ZnCl₂/mol Zn = 0.6118 moles ZnCl₂ produced

For HCl: 18.00 g HCl x 1 mol HCl/36.45g x 1 mol ZnCl₂/2 mol HCl = 0.2469 moles ZnCl₂ produced

HCl is limiting and will dictate the maximum (theoretical) yield of ZnCl₂ which is 0.2469 moles

Theoretical mass ZnCl₂ = 0.2469 moles ZnCl₂ x 136.3 g/mole = 33.65 grams = Theoretical yield

Percent yield = actual yield/theoretical yield (x100%) = 23.0 g/33.65 g (x100%) = 68.4% yield