Question

Compared to a 2.0 M aqueous solution of NaCl at 1 atmosphere, a 3.0 M aqueous solution of NaCl at 1 atmosphere has a

(1) lower boiling point and a higher freezing point
(2) lower boiling point and a lower freezing point
(3) higher boiling point and a higher freezing point
(4) higher boiling point and a lower freezing point

Answer 1

The correct answer is option 4. A 3.0 M aqueous solution of NaCl has a higher boiling point and a lower freezing point than a 2.0 M aqueous solution of NaCl where both are at 1 atmosphere. This is explained by the colligative properties of solutions. For the two properties mentioned, the equation for the calculation of the depression and the elevation is expressed as: ΔT = -Km and ΔT = Km, respectively. As we can see, concentration and the change in the property has a direct relationship.