Question

What is the molal concentration of a solution made by dissolving 34.2 g of sucrose, c12h22o11 (molar mass 342.34 g/mol), in 125 g of water?

Answer 1

0.799 mol

Step-by-step explanation:

Molality is the number of moles of solute in 1 kg of solvent

number of moles of sucrose - mass of sucrose / molar mass

therefore number of moles in 1000 g - 0.0999 / 125 x 1000 = 0.799 mol

Molality of sucrose solution - 0.799 mol

Answer 2

Molality is the number of moles of solute in 1 kg of solvent
number of moles of sucrose - mass of sucrose / molar mass
number of moles of sucrose - 34.2 g / 342.34 g/mol = 0.0999 mol
number of moles in 125 g of water - 0.0999 mol
therefore number of moles in 1000 g - 0.0999 / 125 x 1000 = 0.799 mol/kg
molality of sucrose solution - 0.799 mol/kg