Question

The chemical formula of a salt A is written FexCly.ZH₂O. A sample of this salt of 0.5 grams was dissolved in water. The resulting solution was poured into a chemical beaker containing silver nitrate. The precipitate formed, AgCl, was collected, dried, and weighed as AgNO₃. Calculate:

a) The number of moles of precipitate AgCl when its mass is known to be 0.718 grams.
b) The number of moles of chloride contained in 0.5 grams of compound A.
c) The mass in grams of chloride ions present in 0.5 grams of compound A.

Answer 1

The number of moles of AgCl precipitate formed from 0.718 grams is approximately 0.00501 mol. The number of moles of chloride ions in 0.5 grams of compound A is also 0.00501 mol, and the mass of chloride ions in 0.5 grams of compound A is approximately 0.1776 grams.

Step-by-step explanation:

Calculating Moles and Mass of Precipitate and Chloride Ions

To answer your questions regarding the chemical formula FexCly.ZH₂O and the resultant precipitate AgCl when reacting with AgNO₃, let's go step by step.

a) Moles of precipitate AgCl

The molar mass of AgCl is 143.32 g/mol. Given a mass of 0.718 grams of precipitate:

Moles of AgCl = Mass of AgCl / Molar Mass of AgCl

Moles of AgCl = 0.718 grams / 143.32 g/mol ≈ 0.00501 mol

b) Moles of chloride in 0.5 grams of compound A

Since each mole of AgCl corresponds to one mole of Cl⁻ ions, the moles of chloride ions will be the same as the moles of AgCl precipitate formed.

Moles of Cl⁻ in compound A = 0.00501 mol

c) Mass of chloride ions in 0.5 grams of compound A

To find the mass of chloride ions, multiply the moles of Cl⁻ by the molar mass of Cl, which is 35.45 g/mol:

Mass of Cl⁻ = Moles of Cl⁻ x Molar Mass of Cl

Mass of Cl⁻ = 0.00501 mol x 35.45 g/mol ≈ 0.1776 grams