11.7 g of NaCl and 4.5 g of KBr were dissolved in 47 g of water. What is the molality of NaCl
in the solution?

4.26m

Explanation:

Molality , m, is an unit of concentration in chemistry defined as the ratio between moles of solute (In this case, NaCl) and kg of solvent (In this case, water).

To solve the question we need to find the moles of NaCl and the mass of water in kg:

Moles NaCl -Molar mass: 58.44g/mol-:

11.7g * (1mol / 58.44g) = 0.200 moles

Mass of Water in kg:

47g * (1kg / 1000g) = 0.047kg

Molality is:

0.200 moles / 0.047kg =

4.26m