Question

A reaction occurs in a calorimeter, resulting in the starting and final temperatures shown below. What can you say about the reaction and the enthalpy change (ΔH) during the reaction?
ReactionEnergyAQ1

A. The reaction is endothermic and ΔH is positive.

B. The reaction is endothermic and ΔH is negative.

C. The reaction is exothermic and ΔH is positive.

D. The reaction is exothermic and ΔH is negative.

Answer 1

Answer:

The reaction is exothermic and ΔH is negative

Explanation:

An exothermic reaction is a chemical reaction that releases energy in the form of heat. It is the opposite of an endothermic reaction in which energy is absorbed. It is expressed in a general thermochemical equation: reactants → products + energy.

We can know that a reaction is exothermic by observing the calorimeter to know if there is an increase in temperature. Remember that an exothermic reaction leads to evolution of heat. This is observed physically as a rise in temperature.

The calorimeter initially read 21.0 and finally read 38.8 at the end of the reaction. This implies that heat was given out in the process. The reaction is exothermic and ∆H is negative.