Question

solution contains 174 grams of lithium bromide in 360 grams of water, what is the mole fraction of lithium bromide

Answer 1

Answer:

       $\large\boxed{\large\boxed{0.091}}$

Explanation:

The mole fraction of a component in a mixture is the number of moles of the component divided by the total number of moles of all the components, multiplied by 100.

The symbol X is used to represent the mole fraction.

            $X_A=\dfrac{\text{number of moles of component A}}{\text{number of moles of all the components}}\times 100$

1. Convert masses in grams to number of moles

Formula:

• number of moles = mass in grams / molar mass

a) Lithium bromide

• Chemical Formula: LiBr
• Molar mass: 86.845 g/mol

       $\text{Number of moles}=\dfrac{174g}{86.845g/mol}=2.00mol$

b) Water

• Chemical formula: H₂O

• Molar mass: 18.015 g/mol

      $\text{Number of moles}=\dfrac{360g}{18.015g/mol}=19.98mol\approx 20.0mol$

c) Total number of moles = 2.00 mol + 20.0 mol = 22.0 mol

2. Mole fraction of lithium bromide

           $\text{Mole fraction of lithium bromide}=\dfrac{2.00}{22.0}=0.091$