Properties of Solutions

28) (a) m = 15.0 g Al₂(SO₄)₃

            V = 0.350 L

            Al₂(SO₄)₃(s) 2Al³⁺(aq) + 3SO₄^2-(aq)

            [Al₂(SO₄)₃] = n/V = 15.0 g Al₂(SO₄)₃ x 1 mol Al₂(SO₄)₃/342.14 g Al₂(SO₄)₃/0.350 L

            [Al₂(SO₄)₃] = 0.125 M

      (b) m = 5.25 g Mn(NO₃)₂·2H₂O

            V = 175 mL

            Mn(NO₃)₂·2H₂O(s) Mn²⁺(aq) + 2NO₃^-(aq) + 2H₂O(l)

            [Mn(NO₃)₂·2H₂O] = n/V = 5.25 g Mn(NO₃)₂·2H₂O x 1mol Mn(NO₃)₂·2H₂O/215.00 g Mn(NO₃)₂·2H₂O/(175 mL x 1 L/10³ mL)

            [Mn(NO₃)₂·2H₂O] = 0.140 M

      (c) [H₂SO₄] = 9.00 M

           V_c = 35.0 mL

           V_d = 0.500 L

            H₂SO₄(aq) H⁺(aq) + HSO₄^-(aq)

            n_c = n_d

            [H₂SO₄]_c x V_c = [H₂SO₄]_d x V_d

            [H₂SO₄]_d = [H₂SO₄]_c x V_c/V_d

            [H₂SO₄]_d = 9.00 M x 35.0 mL x 1 L/10³ mL/0.500 L = 0.630 M