Question

Chemical energy stored in the reactants is released as heat when the reaction is exothermic. For an exothermic reaction, the enthalpy change for a reaction is negative. Enthalpy, represented as H, is the heat content of a system. As it is a state function, it depends on the state of the system; hence, it is calculated in the form of change in heat content. Heat change, or enthalpy change, is represented as ΔH; ΔH is a measure of the heat exchanged under conditions of constant pressure.

The enthalpy change for a chemical reaction can be given as

enthalpy change for the reaction=enthalpy change of the products − enthalpy change of the reactants

or

ΔHrxn=(ΔHp−ΔHr).

Part A

Watch the video on the explosive decomposition of nitrogen triiodide, NI3, and determine which of the following statements are correct.

Check all that apply.

Check all that apply.

a. The decomposition of NI3 is an exothermic reaction.

b. In this reaction, heat is absorbed from the surroundings.

c. In this reaction, iodine is produced as one of the products.

d. NI3 is a highly stable compound when it is dry.

e. The enthalpy of NI3 is greater than the enthalpy of the decomposition products.

Answer 1