Question

1 While performing a calorimetry experiment you mix 2 chemical solutions together and the initial temperature of the reagents before the reaction was 22.04"C and final temperature after the reaction was 25.11"C. Circle the correct answers below. Is the chemical reaction exothermic or endothermic? a. Exothermic Endothermic b. Is qoln positive or negative? Negative Positive Is AHrn positive or negative c. Negative Positive You realize that AT needs to be in Kelvin not Celsius. What should you do? d. Convert AT into K from C Use the AT you obtained Retake measurements in K 2. A student is trying to determine the molar enthalpy change for a neutralization reaction and obtained the following temperature data: initial temperature of acid 21.48°C; initial temperature of base 21.53°C; final temperature 18.21 C Is their data correct? In one sentence explain why or why not.

Answer 1

1a) Final temperature is higher than initial, so Exothermic

1b) heat is absorbed by the solution, q_soln = positive

1c) by definition exothermic reaction sign is negative ΔH_rxn = negative

1d) convert ΔT into K from ⁰C

2) Acid-base neutralization reactions are exothermic, heat released and temperature raises, but student data showing fall in final temperature, hence their data is INCORRECT.

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