What is the molal concentration of a solution containing 5.096 g of sodium sulfate in 104.015 g of water?

Answer 1

Molal concentration is defined as moles of solute per kg of solvent.

First find the moles of solute:

5.096 g Na2SO4 x 1 mol/142.04 g = 0.035877 moles

Next, we find the kg of solvent:

104.15 g H2O x 1 kg/1000 g = 0.10415 kg

Finally, we express molality (m) as moles/kg:

m = 0.035877 moles/0.10415 kg = 0.3445 m (to 4 significant figures)