Question

Cual es la fracción molar de una solución que contiene 200 g de hidróxido de magnesio en 225 g de agua

Answer 1

What is the mole fraction of a solution that contains 200 g of magnesium hydroxide in 225 g of water

Answer:

0.215

Explanation:

Given parameters:

Mass of magnesium hydroxide = 200g

Mass of water = 225g

Unknown:

Mole fraction of solution = ?

Solution:

The mole fraction is a measurement of concentration that expresses the number of moles of solute to that of solution.

  Mole fraction = $\frac{mole of solute}{moles of solution}$

A solution is made up of solute and solvent

Number of moles  = $\frac{mass}{molar mass}$

Molar mass of Mg(OH)₂ = 24.3 + 2(16 + 1) = 58.3g/mol

Molar mass of H₂O = 2(1) + 16 = 18g/mol

Number of moles of Mg(OH)₂  = $\frac{200}{58.3}$  = 3.43moles      solute

Number of moles of  H₂O  = $\frac{225}{18}$   = 12.5moles              solvent

Mole fraction  = $\frac{3.43}{3.43 + 12.5}$  = 0.215