Express the concentration of 5% mass of solution of Na_(2)S_(2)O_(3) in terms of (a) molarity (b) molality and © mole fraction of solution. The dens

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Express the concentration of 5% mass of solution of Na_(2)S_(2)O_(3) in terms of (a) molarity (b) molality and © mole fraction of solution. The density of solution at 25^(@)C is gm L^(-1)

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Let the solution contain 5.0g of Na_(2)S_(2)O_(3) and 95.0 g of water. The number of moles of the two constitution are:
 "No. of moles of "Na_(2)S_(2)O_(3)=("Mass of" Na_(2)S_(2)O_(3))/("Molar mass") =((5.0g))/((158.0g mol^(-1))=0.0316 mol
"No. of moles of water"=("Mas of water")/("Molar mass")=((95.0g))/((18.0g mol^(-1)))=5.278 mol
Volume of solution = ("Mass of solution")/("Deensity")=((100.0g))/((1.04 g mL^(-1)))=96.15 mL
Calculation of molarity of solution
"Molality of solution (m)"="(Moles of "(Na_(2)S_(2)O_(3))/("Volume of solution in litres")
 =((0.0316 mol))/((0.095 kg))=0.333 mol kg^(-1)=0.333 m .
Calculation of mole fraction of solute
Mole fraction of solute in solution may calculated as:
"Mole fraction of solute "(x_(B)=n_(B))/(n_(B)+n_(A))=((0.0316 mol))/((0.0316 mol+5.278 mol))
=((0.0316 mol))/((5.3096 mol))=5.95xx10^(-3)