Analyze the potential energy diagram of the reaction shown.
[tex]\begin{array}{l}
CH_4+2 O_2 \rightarrow 2 H_2 O+CO_2+891 kJ
\end{array}[/tex]
[tex]\begin{array}{l}
CO_2+H_2 O
\end{array}[/tex]
Time
Which statements about the reaction are true?
Select all that apply.
A. The reaction is exothermic
B. The reaction is endothermic
C. The equation shows that 891 kJ of energy are released as a product.
D. The equation shows that 891 kJ of energy are absorbed as a reactant.
E. The graph shows that the reactants have greater potential energy than the products.
Answer (1)
The reaction is exothermic because energy is released.
The chemical equation confirms that 891 kJ of energy is released as a product.
The potential energy diagram shows reactants at a higher energy level than products.
Therefore, the true statements are: the reaction is exothermic, the equation shows that 891 kJ of energy are released as a product, and the graph shows that the reactants have greater potential energy than the products.
Explanation
Problem Analysis The problem provides a chemical reaction and its potential energy diagram. We need to analyze the reaction to determine if it's exothermic or endothermic, whether energy is released or absorbed, and how the potential energy of reactants and products compares.
Analyzing the Chemical Equation The chemical equation is: C H 4 + 2 O 2 → 2 H 2 O + C O 2 + 891 k J Since 891 kJ is on the product side, the reaction releases energy. This means the reaction is exothermic, and 891 kJ of energy is released as a product.
Analyzing the Potential Energy Diagram The potential energy diagram shows that the reactants are at a higher energy level than the products. This confirms that the reaction releases energy (exothermic).
Conclusion Based on the analysis:
The reaction is exothermic.
The equation shows that 891 kJ of energy are released as a product.
The graph shows that the reactants have greater potential energy than the products.
Examples
Consider a campfire. Burning wood (reactants) releases heat and light (products), which is an exothermic reaction. The potential energy stored in the wood is higher than the energy in the resulting ash and gases. This released energy can be used to cook food or keep warm, demonstrating a practical application of exothermic reactions.
