Question

If 0.25 moles of KBr is dissolved in 0.5 liters of

heavy water which has a mass of 1,100 grams
per liter, what is the concentration?
Answer in units of m (molal).

Answer 1

[KBr] = 454.5 m

Step-by-step explanation:

m is a sort of concentration that indicates the moles of solute which are contianed in 1kg of solvent.

In this case, the moles of solute are 0.25 moles.

Let's determine the mass of solvent in kg.

Density of heavy water, solvent, is 1.1 g/L and our volume is 0.5L.

1.1 g = mass of solvent / 0.5L, according to density.

mass of solvent = 0.5L . 1.1g/L = 0.55 g

We convert the mass to kg → 0.55 g . 1kg /1000g = 5.5×10⁻⁴ kg

m = mol/kg → 0.25 mol /5.5×10⁻⁴ kg = 454.5 m