What is the molarity of SO 4 2 − ion aqueous solution that contion 34.2 ppm of Al 2 ( SO 4 ) 3 ? (Assume complete dissociation and density of solution 1 g/mL)

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What is the molarity of SO 4 2 − ​ ion aqueous solution that contion 34.2 ppm of Al 2 ​ ( SO 4 ​ ) 3 ​ ? (Assume complete dissociation and density of solution 1 g/mL)

TestHub · Accepted Answer

To find the molarity of SO₄²⁻, first convert 34.2 ppm Al₂(SO₄)₃ to g/L, which is 34.2 mg/L or $34.2 \times 1 0^{- 3}$ g/L.

Molar mass of Al₂(SO₄)₃ = $2 \times 26.98 + 3 \times (32.07 + 4 \times 16.00) = 342.15$ g/mol.

Molarity of Al₂(SO₄)₃ = $\frac{34.2 \times 1 0 ^{- 3} g / L}{342.15 g / m o l} \approx 1 0^{- 4}$ M.

Since Al₂(SO₄)₃ dissociates into 3 SO₄²⁻ ions, molarity of SO₄²⁻ = $3 \times 1 0^{- 4}$ M.

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