A household chlorine bleach is a water solution that is 5.00% by mass sodium hypochlorite. What is the molality of the hypochlorite in the solution? What is the mole fraction of hypochlorite in the solution?

1 Answer
Sep 3, 2017

Answer:

Approximately #0.706m#, and #0.0126#, respectively.

Explanation:

This requires an assumption that there is 5g solute and 95g solvent in 100g solution. Going from this:

#NaClO = (74.5g)/(mol)#

#5.00g * (NaClO)/(74.5g) approx 0.0671mol#

a. Molality is moles of solute over kilograms of solvent; it's a temperature independent measure of solubility.

#(0.0671mol)/(.0950kg) approx 0.706m#

b. Mole fraction is the ratio of moles of solvent or solute per total moles of components of the solution, thus:

#95.0g * (H_2O)/(18.0g) approx 5.28mol#

#(0.0671mol)/(0.0671mol+5.28mol) approx 0.0126#