A chemist measures the energy change ΔH during the following reaction:2NH3(g)→N2(g)+3H2(g) =ΔH160.kJUse the information to answer the following questions.

1. Break Down the Problem

To answer questions based on the given reaction and energy change, we need to analyze the following:

1. What does the ΔH value signify in relation to the reaction?
2. How does the energy change relate to the stoichiometry of the reaction?
3. If necessary, can we determine the ΔH for different amounts of reactants or products?

2. Relevant Concepts

• The enthalpy change (ΔH) represents the heat absorbed or released under constant pressure during a chemical reaction.
• A positive ΔH indicates that the reaction is endothermic (absorbs heat).
• The stoichiometry of the reaction gives the molar ratios of the reactants and products.

3. Analysis and Detail

The reaction provided is: $2 \, \text{NH}_3(g) \rightarrow \text{N}_2(g) + 3 \, \text{H}_2(g) \quad \Delta H = +160 \, \text{kJ}$ This means when 2 moles of ammonia (NH3) decompose, they absorb 160 kJ of energy.

• For 1 mole of NH3: Since ΔH applies to 2 moles of NH3, we can calculate the energy change for 1 mole:

$\Delta H \text{ for } 1 \, \text{mol NH}_3 = \frac{160 \, \text{kJ}}{2} = 80 \, \text{kJ}$

4. Verify and Summarize

This means that for every mole of NH3 that decomposes, the reaction absorbs 80 kJ. If we needed to calculate the energy change for different quantities, we would adjust the ΔH value accordingly based on the stoichiometry.

Final Answer

The enthalpy change for the decomposition of 2 moles of ammonia is +160 kJ, which implies that each mole absorbs 80 kJ of energy during the reaction.