Question

A chemist performs the following reaction:

PCl5 (aq) + 4H2O (l) ⟶ H3PO4 (aq) + 5HCl (aq)
If she has 26.4 g of PCl5, what mass of water should she react to use up all of the
PCl5?

Looking for an in-depth step by step, please

Answer 1

9.17 g

Step-by-step explanation:

1) Calculate mols of PCl5

PCl5 (aq) + 4H2O (l) ⟶ H3PO4 (aq) + 5HCl (aq)

Mass of PCl5: 26.5g

Molar Mass of PCl5 208.24g/mol

Mol of PCl5 = Mass PCl5 /Molar mass PCl5 = 26.5g / (208.24g/mol) = 0.127257011 mol

2) Calculate mols of water needed to react

Mols of H2O per 1 Mols of PCl5 = 4 (because 4 water is needed to Phosphorus pentachloride).

Mols of H2O = Mol of PCl5 * 4 = 0.127257011 * 4 = 0.509028044 mols

3) Calculate Grams of water needed to react

Mols of H2O = 0.509028044 mols

Molar Mass of H2O = 18.015 g/mol

Mass of H2O = Mols of H2O * Molar Mass of H2O

= 0.509028044 mols* 18.015 g/mol = 9.17014021 g

sf = 3

9.17 g