The figure depicting the dissolution of ammonium chloride in water illustrates an endothermic process. A gradual increase, peak, and subsequent decrease in dissolution imply energy absorption, leading to a cooling effect during the process.
The figure you described, showing a gradual increase, a peak, and then a decrease in the dissolution of ammonium chloride in water, suggests that the process is endothermic. Here's how the figure aligns with the endothermic nature of the dissolution:
1. **Gradual Increase (Middle of the Graph):** Initially, as ammonium chloride dissolves in water, energy is absorbed from the surroundings. The gradual increase in dissolution suggests that heat is being absorbed, leading to a cooling effect.
2. **Linear Region (After Initial Dissolution):** The linear portion of the graph indicates a relatively constant rate of dissolution, but it's important to note that the dissolution process continues to be endothermic during this phase.
3. **Peak and Decrease:** The peak represents the point where the dissolution process is at its maximum. This occurs because as more ammonium chloride is dissolved, the solution becomes saturated, and further dissolution becomes less favorable. The decrease in dissolution after the peak suggests that the endothermic process is slowing down.
4. **Inverted Half U Shape:** The inverted half U shape, characterized by a decrease after reaching a maximum, is indicative of an endothermic reaction. The system absorbs energy from the surroundings, leading to the observed cooling effect.
5. **Linear Region Again:** The final linear portion of the graph suggests that the dissolution process has slowed down, and the solution is becoming more dilute.
In summary, the figure illustrates the characteristic behavior of an endothermic process, where energy is absorbed during the dissolution of ammonium chloride in water, resulting in a cooling effect. The peak and subsequent decrease indicate that the process becomes less favorable as the solution becomes saturated.