Question

Calculate the mole fraction of NaOH in a solution containing 20g of NaOH per 360g of H2O

Answer 1

Given :

Mass of NaOH = 20g

Mass of water = 360g

To Find :

Mole fraction of NaOH in the solution.

Basic Information :

$\star$ Mole fraction (x) : Ratio of number of moles of one component to the total number of moles of all the components.

Effect of temperature : No effect

Formula : $\underline{\boxed{\bf{\orange{x_a=\dfrac{n_a}{n_a+n_b}}}}}$

Calculation :

First we need to find number of moles of each component.

Moles of NaOH : 20/40 = 0.5

Moles of H₂O : 360/18 = 20

★ Mole fraction of NaOH :

$:\implies\sf\:x_{NaOH}=\dfrac{n_{NaOH}}{n_{NaOH}+n_{H_2O}}$

$:\implies\sf\:x_{NaOH}=\dfrac{0.5}{0.5+20}$

$:\implies\sf\:x_{NaOH}=\dfrac{0.5}{20.5}$

$:\implies\:\boxed{\bf{\purple{x_{NaOH}=0.024}}}$

Answer 2

Given :

Mass of NaOH = 20g

Mass of water = 360g

To Find :

Mole fraction of NaOH in the solution.

Basic Information :

$\star$ Mole fraction (x) : Ratio of number of moles of one component to the total number of moles of all the components.

Effect of temperature : No effect

Formula : $\underline{\boxed{\bf{\orange{x_a=\dfrac{n_a}{n_a+n_b}}}}}$

Calculation :

First we need to find number of moles of each component.

Moles of NaOH : 20/40 = 0.5

Moles of H₂O : 360/18 = 20

★ Mole fraction of NaOH :

$:\implies\sf\:x_{NaOH}=\dfrac{n_{NaOH}}{n_{NaOH}+n_{H_2O}}$

$:\implies\sf\:x_{NaOH}=\dfrac{0.5}{0.5+20}$

$:\implies\sf\:x_{NaOH}=\dfrac{0.5}{20.5}$

$:\implies\:\boxed{\bf{\purple{x_{NaOH}=0.024}}}$