What is the molarity of a solution prepared by dissolving 284 grams of sodium sulfate in 2500 mL of water?

Answer 1

Can't tell because we don't know the final volume of the solution. The 284 g of solute will certainly add to the volume of 2500 ml, but if we assume it doesn't then we proceed as follows:

Molarity = moles solute/L solution.

moles solute = 284 g Na2SO4 x 1 mol Na2SO4/142 g = 2.0 moles

Liters of solution (assuming no change in volume) = 2500 ml x 1 L/1000 ml = 2.5 L

Molarity = 2.0 mol/2.5 L = 0.8 M