Question

PLS HELP Students in a chemistry class added 5 g of Zinc (Zn) to 50 g of hydrochloric acid (HCl). A chemical reaction occurred that produced zinc chloride (ZnCl2) and 6 g of hydrogen gas (H2).
Zn+ HCl → ZnCl2 + H2

What is the mass of Zinc Chloride (ZnCl2)?

A. 49 g

B. 55 g

C. 61 g

D. Not enough information to determine the mass of ZnCl2

Answer 1

Answer: In simplest case mass of reactants is same as mass of products.

Without thinking this question deeper, mass of ZnCl2 would be 49, but..

Explanation: Reaction should be  Zn + 2 HCl ⇒ ZnCl2 + H2

Amount of zinc is  5 g / 65,38 g/mol = 0,076476 mol and amount

of Hydrogen Chloride is 50 g / 36.458 g/mol = 1,371 mol.

Althought HCl is needed 0.152 moles, zinc is an limiting reactant.

So it is possible to produce only 0.076476 mol Hydrogen and its mass

is 0.154 g.  Mass of ZnCl2 would be 0.076476 mol · (65.38 + 2·35.45) =

 10.42 g