Write the balanced equation for the synthesis of hydrochloric acid. How many moles of chlorine are required for the production of 72.92 g hydrochloric acid?

a. H₂(g) + Cl₂(g) ⇒ 2HCl (g)

HCl (g) + H₂O (l) ⇒ H₃O⁺ (aq) + Cl⁻ (aq)

b. 0.999 mol

Explanation:

a. Write the balanced equation for the synthesis of hydrochloric acid.  

The balanced equation for the synthesis of hydrochloric acid is thus

H₂(g) + Cl₂(g) ⇒ 2HCl (g)

HCl (g) + H₂O (l) ⇒ H₃O⁺ (aq) + Cl⁻ (aq)

b.  How many moles of chlorine are  required for the production of 72.92 g hydrochloric acid?

We need to find the number of moles of HCl contained in 72.92 g. So, molar mass M of HCl = molar mass of hydrogen + molar mass of chlorine

molar mass of hydrogen = 1 g/mol

molar mass of chlorine = 35.5 g/mol

So, molar mass of HCl = 1 g/mol + 35.5 g/mol = 36.5 g/mol.

We now find the number of moles n of HCl in 72.92 g from n = m/M where m = mass of HCl = 72.92 g

n = 72.92 g/36.5 g/mol = 1.998 mol.

From the balanced chemical equation, 1 mol of chlorine atoms produces 2 moles of hydrogen chloride gas. Therefore, the number of moles of chlorine atoms produces 1.998 mol HCl or 72.92 g HCl is 1 mol × 1.998 mol/2 mol = 0.999 mol