Question

When $CuS{O_4}$ is added to a solution of ammonia?
A. The freezing point is lowered
B. Freezing point is raised
C. The boiling point is raised
D. Both (1) and (2)

Answer 1

Hint: Both Boiling point and freezing point are colligative properties and instead of the nature of chemical substance it depends on the number of solute and solvent molecules in a solution.

Complete step by step answer:
When copper sulphate is added to the solution of ammonia, it tends to form complex $[Cu{(N{H_3})_4}]S{O_4}$, as a result, the number of the particle is a decrease in the solution. Thus there is a decrease in van’t Hoff factor. Since freezing point and elevation in boiling point is a colligative property, thus these are directly proportional to the van’t Hoff factor. Since the decrease in the number of particles raises in the freezing point and decreases in boiling point thus we can say adding copper sulphate into the solution of ammonia freezing point raised.

So, the correct answer is Option B.

Additional information:
Van’t Hoff factor is defined as the ratio of the experimental value of the colligative property to the calculated value of the colligative property. Van’t Hoff factor is denoted by $i$. Since the colligative property is inversely proportional to the molecular mass of the solute, we can also say that the colligative property is also defined as the ratio of normal molecular mass to the abnormal molecular mass.

Note: Copper Sulphate also known as Bluestone is one of the most widely used and best-known copper salts and it has a range of applications in industries, agriculture. It is used as a fungicide, steriliser and also as a preservative. It is also used as an electrolyte in copper refining.