The given reaction is: NH4HS(s) → NH3(g) + H2S(g); ΔH° = 93 kJ.
To determine which of the following statements is true for this reaction, let's consider each option:
1. "The reaction is exothermic."
This statement is true because the given value of ΔH° is positive (+93 kJ), indicating that the reaction releases energy in the form of heat. An exothermic reaction is one in which energy is released.
2. "The reaction is endothermic."
This statement is false. As mentioned earlier, the positive value of ΔH° (+93 kJ) indicates that the reaction is exothermic, not endothermic. An endothermic reaction would have a negative value of ΔH°.
3. "The reaction absorbs energy from the surroundings."
This statement is false. An exothermic reaction releases energy to the surroundings, rather than absorbing energy. In this case, the given positive value of ΔH° (+93 kJ) indicates that energy is released.
Based on the analysis, the correct statement is: "The reaction is exothermic." This means that the reaction releases energy in the form of heat.