Question

When solutions containing silver ions and chloride ions are mixed, silver chloride precipitates: Ag+(aq)+Cl−(aq)→AgCl(s)ΔH=−65.5kJ

Calculate ΔH for formation of 0.490 mol of AgCl by this reaction.

Calculate ΔH for the formation of 7.50 g of AgCl.

Calculate ΔH when 9.23×10⁻⁴ mol of AgCl dissolves in water.

Answer 1

The reaction is

Ag⁺_(aq) + Cl^-_(aq) → AgCl_(s) ΔH = −65.5kJ

for 1 mole of AgCl   ΔH = −65.5kJ then for

ΔH for formation of 0.490 mol of AgCl

(0.490)$\times$(-65.5) = -32.095 KJ

ΔH for the formation of 7.50 g of AgCl.

molar mass of AgCl = 143.32g/mol

7.50 gm = 7.50/143.32 = 0.05233 mole

(0.05233)$\times$(-65.5) = -3.4276 KJ

ΔH when 9.23×10^-4 mol of AgCl dissolves in water.

rection is reversed thus,

AgCl_(s) → Ag⁺_(aq) + Cl^-_(aq) ΔH = +65.5kJ

(9.23×10^-4)$\times$(65.5) = 0.06045 KJ