3. A student conducts an experiment where they dissolve 1 g each of several substances in 50 mL of water. They have 12 identical plastic cups of water and place 1 g of salt into three of the cups, 1 g of sugar into three of the cups, and 1 g of baking soda into three of the cups. The three remaining cups contain only water. All the cups are put in a freezer, and the temperature of the solution in each cup is recorded every 15 minutes for 4 hours. What question is the student most likely investigating?
Answer: A
The student is most likely investigating the effect of different concentrations of solute on the freezing point of water.
The experiment focuses on how the addition of different solutes (salt, sugar, and baking soda) affects the freezing point of water. This aligns with the objective of determining how varying concentrations influence the physical properties of the solution.
A) What effect do different concentrations of solute have on the freezing point of water?
This option is correct as the student is specifically examining how the addition of different substances (solutes) to water alters its freezing point, which is a direct consequence of the colligative properties of solutions.
B) How does the volume of water affect the rate at which it cools?
This option is incorrect because the experiment does not manipulate the volume of water; all cups contain the same volume (50 mL). Thus, the focus is not on how volume affects cooling but rather on the impact of solutes.
C) What effect does cooling have on the solubility of different solutes?
This option is incorrect as the experiment does not investigate how cooling affects solubility. Instead, it examines how solutes impact the freezing point of water, making this focus misaligned with the experiment's design.
D) How is the cooling rate of water affected by different solutes?
This option is also incorrect because the primary goal is not to measure the cooling rate but to observe changes in freezing point due to the presence of solutes. While cooling rate may be a factor, it is not the central question being investigated.
Conclusion
The correct answer, A, directly addresses the core inquiry of the experiment regarding how different solutes influence the freezing point of water. All other options either misinterpret the experiment's focus or introduce variables that are not being tested, thereby reinforcing why A is the definitive correct choice.