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.
3. If an additional trial had been done in which 25 g of LiCl had been added to 75 g of H2O, △T would most likely have been:
Your Answer is
Correct Answer is C
Explanation
Look at the line of 75 g H2O in figure 1, judge according to the slope of the line segment, when the abscissa is 25g, the ordinate is close to but still less than 40 °C