Question

If 56.8 mL of BaCl2 solution is needed to precipitate all the sulfate ion in a 752 mg sample of Na2SO4, what is the molarity of the solution?

Express the molarity to three significant digits.

Answer 1

The balanced equation for the reaction between BaCl2 and Na2SO4 is

BaCl2(aq) + Na2SO4(aq) ------> BaSO4(s) + 2NaCl(aq)

1:1 molar reaction

mole = mass / molar mass

number of moles of Na2SO4 = 0.752g / 142.04g/mol = 0.005294mol

moles of BaCl2 present in the solution = 0.005294mol

molarity = number of moles of solute per liter of solution

molarity of the solution = ( 0.005294mol/56.8ml) × 1000ml

= 0.0932M