Question

In the lab, a student prepared a solution of ammonium chloride in water. The student placed 9.5 g NH4Cl in a beaker and added 35.0 g of H20. The initial temperature of the water was 27°C. The student stirred the mixture, and the final temperature of the solution was 16°C. In this solution, the substance that is being dissolved is:

a) H2O; solvent
b) NH4Cl; solute
c) NH4Cl; solvent
d) H2O; solute

Answer 1

The substance that is being dissolved, ammonium chloride (NH4Cl), is the solute, while water (H2O) is the solvent. Hence, the correct answer is option b) NH4Cl; solute.

Step-by-step explanation:

When ammonium chloride (NH4Cl) is added to water and stirred, it dissolves in the water. The substance that is being dissolved in this scenario is the ammonium chloride, making it the solute. The water (H2O), which the solute is dissolved in, is known as the solvent. Therefore, the correct answer to the question is option b) NH4Cl; solute. This is because the solute is the substance that is being dissolved, whereas the solvent is the substance that does the dissolving, typically present in greater amount.

In this case, water is the substance that is present in a larger quantity than ammonium chloride and hence serves as the medium in which the solute is being dissolved. The fact that the temperature drops when ammonium chloride is dissolved indicates an endothermic process, meaning that the dissolution absorbs heat from the surroundings, causing the temperature to decrease.