Question

If 20 grams of Zinc phosphate reacts with excess hydrochloric acid and produces 18 grams of Zinc chloride what is the percent yield?

Zn3(PO4)2 + 6HCl —> 3ZnCl2 + 2H3PO4

Answer 1

`Y=85\%`

Step-by-step explanation:

Hello!

In this case, since we know the balanced chemical reaction, we are first able to realize there is a 1:3 mole ratio between zinc phosphate and zinc chloride; it means that we can first compute the moles of the desired product via stoichiometry:

`n_(ZnCl_2)=20gZn_3(PO_4)_2*(1molZn_3(PO_4)_2)/(386.11gZn_3(PO_4)_2)*(3molZnCl_2)/(1molZn_3(PO_4)_2)=0.16gZnCl_2`

Next, since those moles are associated with the theoretical yield of zinc chloride, we obtain the corresponding mass:

`m_(ZnCl_2)^(theoretical)=0.16molZnCl_2*(136.29gZnCl_2)/(1molZnCl_2) =21gZnCl_2`

Finally, we compute the percent yield by diving the actual yield (18 g) by the theoretical yield:

`Y=(18g)/(21g)*100\%\\\\Y=85\%`

Best regards!