Question

Calculate the molality when20g of Na2 Co3 present in 250g of solvent​

Answer 1

Answer:

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

Molality=

mass of solvent in kg

number of moles of solute

Let W g of sodium carbonate are dissolved.

The molar mass of Na

2

CO

3

=2(23)+12+3(16)=46+12+48=106 g/mol

The number of moles of Na

2

CO

3

=

106 g/mol

W g

= 0.009434 W mol

Mass of water = 250 g= 0.250 kg

0.1 m=

0.250 kg

0.009434 W mol

W= 2.65 g

Hence, 2.65 grams of Na

2

CO

3

should be dissolved in 250 grams of water to prepare 0.1 m solution