Question

What is the molarity of a solution prepared by diluting 250 mL of a 40% H2SO4 solution to 1 Liter? The density of the stock solution is 1.17 g/mL

Answer 1

Answer:

1.195 M.

Explanation:

• We can calculate the concentration of the stock solution using the relation:

M = (10Pd)/(molar mass).

Where, M is the molarity of H₂SO₄.

P is the percent of H₂SO₄ (P = 40%).

d is the density of H₂SO₄ (d = 1.17 g/mL).

molar mass of H₂SO₄ = 98 g/mol.

∴ M of stock H₂SO₄ = (10Pd)/(molar mass) = (10)(40%)(1.17 g/mL) / (98 g/mol) = 4.78 M.

• We have the role that the no. of millimoles of a solution before dilution is equal to the no. of millimoles after dilution.

∴ (MV) before dilution = (MV) after dilution

M before dilution = 4.78 M, V before dilution = 250 mL.

M after dilution = ??? M, V after dilution = 1.0 L = 1000 mL.

∴ M after dilution = (MV) before dilution/(V after dilution) = (4.78 M)(250 mL)/(1000 mL) = 1.195 M.