Question

Aqueous hydrochloric acid

HCl

will react with solid sodium hydroxide

NaOH

to produce aqueous sodium chloride

NaCl

and liquid water

H2O

.Suppose 36.1 g of hydrochloric acid is mixed with 56. g of sodium hydroxide. Calculate the maximum mass of water that could be produced by the chemical reaction. Be sure your answer has the correct number of significant digits.

Answer 1

The balanced reaction

HCl + NaOH = NaCl + H2O

Mass of HCl = 36.1 g

Moles of HCl = mass/molecular weight

= (36.1 g) / (36.5 g/mol)

= 0.989 mol

Mass of NaOH = 56.0 g

Moles of NaOH = mass/molecular weight

= (56.0 g) / (40 g/mol)

= 1.40 mol

From the stoichiometry of the reaction

1 mol HCl required = 1 mol NaOH

0.989 mol HCl required = 0.989 mol NaOH

We have more moles (1.40) of NaOH than required (0.989)

Excess reactant = NaOH

Limiting reactant = HCl

Moles of water produced = moles of HCl reacted = 0.989 mol

Mass of water produced = moles x molecular weight

= 0.989 mol x 18 g/mol

= 17.8 g