Question

Students in a chemistry class added 5 g of Zinc to 50 g of hydrochloric acid. A chemical reaction occurred that produced zinc chloride and 6 g of hydrogen gas. What is the mass of the zinc chloride?

Answer 1

Answer:

Mass = 11 g

Explanation:

Given data:

Mass of Zn = 5 g

Mass of HCl = 50 g

Mass of hydrogen gas produced = 6 g

Mass of zinc chloride produced = ?

Solution:

Chemical equation:

Zn + 2HCl    →   ZnCl₂ + H₂

Number of moles of Zn:

Number of moles = mass / molar mass

Number of moles = 5 g / 65.38 g/mol

Number of moles = 0.08 mol

Number of moles of HCl :

Number of moles = mass / molar mass

Number of moles = 50 g / 36.5 g/mol

Number of moles = 1.4 mol

Now we will compare the moles of both reactant with zinc chloride.

              Zn           :           ZnCl₂

               1             :             1

              0.08       :        0.08

            HCl          :         ZnCl₂

              2            :           1

             1.4          :         1/2×1.4 =0.7 mol

The number of moles of zinc chloride produced by Zn are less so it will limiting reactant.

Mass of zinc chloride:

Mass = number of moles × molar mass

Mass = 0.08 mol × 136.3 g/mol

Mass = 11 g