Question

Calculate Molality for 4M Na2CO3 solution with Density = 1.02 g/mL​

Answer 1

Answer:

Molality of the 4M Na2CO3 solution is 1.09m.

Explanation:

Given:

Molarity = 4M Na2CO3 solution

Density = 1.02g/mL

By definition we know that Molarity is the no. of moles present in per litre of solution i.e., 1M solution has 1 mole of Na2CO3 for 1000ml of solution.

∴ mass of solute is mass of 1 mole of Na2CO3 = 46+12+48 = 106 gm.

                 volume of solution = 1000 ml as per definition.

mass = density X volume

mass = 1.02×1000 = 1020 gm

Mass of solvent = mass of solution - mass of solute

                         = 1020 - 106= 914gm.

Molality is the no. of mole of solute per kg of solvent

m =  $\frac{1}{914}$ x 1000 = 1.09m.

∴ Molality of the 4M Na2CO3 solution is 1.09m.