Passage I

When a substance dissolves in H2O, heat is either absorbed from or given off to the solution. “Experiments were done in which a known mass of a solute was added to a known mass of H2O at a known initial temperature (Ti) in a closed, insulated container. When the maximum 'temperature change of the solution had occurred, the final temperature (Tf) was recorded. The maximum temperature change (△T) was then calculated as follows:

△T = Tf - Ti

Figures 1 and 2 show the results for lithium chloride (LiCl) and ammonium nitrate (NH4NO3), respectively. In each trial, all of the solute completely dissolved.

5. 5.Based on Figures 1 and 2, which of the following combinations of a solute and H2O at a known Ti would produce the greatest increase in temperature?

Answer and Explanation

Your Answer is

Correct Answer is A

Explanation

Because the increase temperature is required in the question stem, you can only choose LiCl, and exclude the C&D option;

Observe figure1 again, compare the slopes of the three lines in the figure, and find that H2< The smaller the amount of /sub>0, the larger the ΔT, so choose 5g H2O

of option A