1.
In order for a solution to be an electrolyte, the solute must
Correct Answer
D. Consist of positive and negative ions.
Explanation
An electrolyte is a substance that conducts electricity when dissolved in a solvent. This is because it consists of positive and negative ions that are free to move and carry electric charge. A molecular compound, on the other hand, consists of neutral molecules held together by covalent bonds and does not dissociate into ions in solution. Therefore, for a solution to be an electrolyte, it must consist of positive and negative ions.
2.
Which statement best describes a supersaturated solution? A solution which -
Correct Answer
A. Contains more solute than is normally possible.
Explanation
A supersaturated solution is a solution that contains more solute than is normally possible at a given temperature and pressure. This means that the solution is holding more solute than it should be able to dissolve, creating an unstable condition.
3.
15 g of sugar cubes are dissolved in 120 g of water at 20o C. What could be done to increase the rate of dissolution?
Correct Answer
B. Stir the mixture
Explanation
Stirring the mixture can increase the rate of dissolution because it helps to increase the contact between the sugar cubes and water. When the mixture is stirred, it creates turbulence in the liquid, causing the sugar cubes to break down and mix with the water more quickly. This allows the sugar molecules to spread out and interact with the water molecules, leading to a faster dissolution process.
4.
Which method below will not speed up the rate of salt dissolving in water?
Correct Answer
B. Decreasing the temperature of the solvent
Explanation
Decreasing the temperature of the solvent will not speed up the rate of salt dissolving in water because solubility generally decreases with decreasing temperature. When the temperature decreases, the kinetic energy of the particles decreases, resulting in fewer collisions between the solvent molecules and the solute particles. As a result, the rate of dissolution decreases, and it takes longer for the salt to dissolve in water.
5.
The graph below illustrates the solubility of potassium chloride in water at a variety of temperatures. At what temperature does 30 g of KCl dissolved in 100 g of water create a saturated solution?
Correct Answer
A. 10 degrees C
Explanation
According to the graph, at 10 degrees C, the solubility of potassium chloride in water is approximately 30 g/100 g of water. This means that at this temperature, 30 g of KCl can dissolve in 100 g of water, creating a saturated solution.
6.
At what temperature would carbon dioxide gas, CO2(g), be most soluble in 100 g of water?
Correct Answer
A. 10 degrees C
Explanation
Carbon dioxide gas is most soluble in water at lower temperatures. As the temperature decreases, the solubility of gases in water generally increases. Therefore, at 10 degrees C, carbon dioxide gas would be most soluble in 100 g of water.
7.
Which of the following will dissolve at the fastest rate?
Correct Answer
C. 15 g of granulated sugar in 120 g of water at 60o C.
Explanation
Granulated sugar dissolves faster than sugar cubes because it has a larger surface area exposed to the water. Additionally, at higher temperatures, the kinetic energy of the water molecules increases, leading to faster dissolution. Therefore, 15 g of granulated sugar in 120 g of water at 60o C will dissolve at the fastest rate.