Answer to Question #345702 in General Chemistry for Kaushi

Question

An aqueous solution K2SO4.Cr(SO4)3.12H2O contains 2.08gdm-3 of Cr3+ ions .what is the SO4^2- concentration in moldm-3 in this solution

Answer 1

K₂SO₄ • Cr(SO₄)₃ • 12 H₂O

In the above substance, 1 mole of Cr³⁺ ion corresponds to 4 moles of (SO₄)^2- ion. that is, since the (SO₄)^2- ion is 4 times larger than the Cr³⁺ ion, its concentration is also 4 times higher:

M_r (Cr) = 54 g/mol

2,08 g/dm³ / 54 g/mol = 0,0385 mol/dm³

0,0385 * 4 = 0,154 mol/dm³

ANSWER: 0,154 mol/dm³