Question

20 gm of Naox is dissolved in 150 gm of water. Calculate the mass % of Naox and water.​

Answer 1

Explanation:

Molality = Moles of solute/ kilograms of solvent

Moles of NaOH =( 20 gm of NaOH × 1 mole of NaOH) ÷ molar mass of NaoH

= 20*1/40 = 1/2 = 0.5 moles of NaOH

Density =mass/ Volume

Density of water = 1.08 g/ cm^3

Volume = 500 cm^3 ( given)

1.08 =mass/ volume

1.08 = mass/ 500

1.08× 500 = mass

Mass of water = 500gm ( approximately)

Kilogram of water = (500g of water x 1 kg of water)÷1000 gm of water.

= 500/1000=5/ 10 = 1/2 = 0.5 Kg of water

Molality = moles of solute/ kilograms of solvent

= 0.5/0.5 = 1mole/kgm