Consider the following reaction wherein lead sulfide precipitates when a solution containing lead ions and sulfide ions is mixed:
Pb²⁺(aq) + S^2–(aq) → PbS(s)           ΔH = –131.8 kJ
(a) Determine the ΔH for the formation of 0.215 mol of PbS.
(b) Determine the ΔH for the formation of 3.50 g of PbS.
(c) Determine the ΔH when 3.65×10^–4 mol of PbS is dissolved in water.

• A. (a) ΔH = +33.1 kJ; (b) ΔH = +461 kJ; (c) ΔH = –5.04 J
• B. (a) ΔH = –33.1 kJ; (b) ΔH = –461 kJ; (c) ΔH = +5.04 J
• C. (a) ΔH = +28.3 kJ; (b) ΔH = +1.93 kJ; (c) ΔH = –48.1 J
• D. (a) ΔH = –28.3 kJ; (b) ΔH = –1.93 kJ; (c) ΔH = 48.1 J
• E. (a) ΔH = –33.1 kJ; (b) ΔH = +1.93 kJ; (c) ΔH = –5.04 J

Answer: (D)