How do the results show that dissolving ammonium nitrate in water is endothermic?
How to approach this question
Recall the definitions of endothermic and exothermic reactions.\n- **Exo**thermic reactions release heat, causing the temperature of the surroundings to **in**crease (like an **exo**dus of heat).\n- **Endo**thermic reactions take in heat from the surroundings, causing the temperature of the surroundings to **de**crease (heat goes **in**to the reaction).\nLook at the data table or your graph. What happens to the temperature when ammonium nitrate is added?
Full Answer
The temperature of the solution decreases.
An endothermic process is one that absorbs energy (usually in the form of heat) from its surroundings. As the process takes in heat from the water, the temperature of the water (the surroundings) drops. The results in Table 6 and the plotted graph clearly show that as more ammonium nitrate is dissolved, the temperature of the solution decreases. This decrease in temperature is the evidence that the process is endothermic.
Common mistakes
✗ Saying the reaction is exothermic.\n✗ Just stating the numbers without explaining what they show (i.e., a temperature decrease).
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