Two solutions, initially at 24.60°C, are mixed in a coffee cup calorimeter. When a 100.0 mL volume of 0.100 M AgNO3 solution is mixed with a 100.0 mL sample of 0.200 M NaCl solution, the temperature in the calorimeter rises to 25.30°C. Determine the type of reaction that occurred.

• A. Endothermic reaction
• B. Exothermic reaction
• C. No reaction occurred
• D. Isothermal process

Answer: (B)

Verified step by step guidance

1. Identify the chemical reaction that occurs when AgNO3 and NaCl solutions are mixed. The reaction is: AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq). This is a precipitation reaction where solid AgCl is formed.
2. Determine the initial and final temperatures of the solution. The initial temperature is 24.60°C, and the final temperature after mixing is 25.30°C.
3. Calculate the change in temperature (ΔT) by subtracting the initial temperature from the final temperature: ΔT = 25.30°C - 24.60°C.
4. Analyze the temperature change. Since the temperature of the solution increased, this indicates that heat was released during the reaction, which is characteristic of an exothermic reaction.
5. Conclude the type of reaction based on the temperature change. Since the temperature increased, the reaction is exothermic, meaning it releases heat to the surroundings.