The reaction between ammonium sulfate and calcium hydroxide is given below. (NH₄)₂SO₄ + Ca(OH)₂ --> 2NH₃ + CaSO₄ + 2H₂O From the balance equation, we can conclude that every 74 g of calcium sulfate reacted with enough amount of ammonium sulfate will yield 34 grams of ammonia. From the given amount, (20 g calcium sulfate) x (34 grams ammonia / 74 g calcium sulfate) = <em>9.19 g ammonia</em>