Question

Find molality of pure water (H2O = 18)

Answer 1

$\checkmark$ Given:

Molar mass of Water = 18 g/mol

$\checkmark$ To Find:

Molality of pure water

$\checkmark$ Solution:

We know that,

$\red{\bigstar \ \boxed{\rm Molality= \dfrac{No. \ of \ moles\ of \ Water}{Weight \ of \ solvent \ (Kg)}}}$

Here,

Solvent = Water

According to question,

We are asked to find the Molality

Given that,

• Molar mass of Water = 18 g/mol

Also,

Density of Water = 1 Kg/L

So,

• Mass of water = 1 x 1000 g = 1 Kg

Hence,

Number of moles of water

$\blue{\rm \implies No. \ of \ moles \ of \ Water= \dfrac{1000}{18}}$

$\green{\rm \implies No. \ of \ moles \ of \ Water = 55.55 \ moles}$

Therefore,

$\orange{\rm \implies Molality =\dfrac{55.55}{1} \ m}$

Hence,

$\checkmark$ Molality of pure water is 55.55 m