Question

Excess Na₂SO₄(aq) is added to a 3.93×10² mL sample of industrial waste containing Ba²⁺ ions. If 50.5 g of BaSO₄(s) are precipitated from the reaction, what was the molar concentration of Ba²⁺ in the original sample?

Answer 1

The molar concentration of Ba²⁺ in the original sample is 0.551 M.

Step-by-step explanation:

To find the molar concentration of Ba²⁺ in the original sample, we can use the equation:

Ba²⁺(aq) + SO₄²⁻(aq) → BaSO₄(s)

From the equation, we can see that 1 mole of Ba²⁺ reacts with 1 mole of SO₄²⁻ to form 1 mole of BaSO₄. Using this information, we can calculate the number of moles of BaSO₄ that formed from the 50.5 g of BaSO₄ precipitated:

Moles of BaSO₄ = Mass of BaSO₄ / Molar mass of BaSO₄ = 50.5 g / 233.43 g/mol = 0.2161 mol BaSO₄

Since 1 mole of Ba²⁺ reacts with 1 mole of SO₄²⁻, the number of moles of Ba²⁺ in the original sample is also 0.2161 mol. The molar concentration of Ba²⁺ can then be calculated by dividing the moles of Ba²⁺ by the volume of the original sample:

Molar concentration of Ba²⁺ = Moles of Ba²⁺ / Volume of original sample = 0.2161 mol / 3.93×10² mL = 0.551 M