Question

Classify each of the following as exothermic or endothermic and give the $\Delta H$ for each: a. $\mathrm{CH}_{4}(\mathrm{~g})+2 \mathrm{O}_{2}(\mathrm{~g}) \stackrel{\Delta}{\longrightarrow} \mathrm{CO}_{2}(g)+2 \mathrm{H}_{2} \mathrm{O}(g)+802 \mathrm{~kJ}$ b. $\mathrm{Ca}(\mathrm{OH})_{2}(s)+65.3 \mathrm{~kJ} \longrightarrow \mathrm{CaO}(s)+\mathrm{H}_{2} \mathrm{O}(l)$ c. $2 \mathrm{Al}(s)+\mathrm{Fe}_{2} \mathrm{O}_{3}(s) \longrightarrow \mathrm{Al}_{2} \mathrm{O}_{3}(s)+2 \mathrm{Fe}(l)+850 \mathrm{~kJ}$

Name: Problem 91, Chapter 7: General, Organic, Biological Chemistry: Structures of Life
Uploaded: 2022-02-21T23:21:31-08:00
Duration: 1 min 12 s
Channel: Nicole Smina
Description: Classify each of the following as exothermic or endothermic and give the ΔH for each: a. CH4( g)+2 O2( g) Δ⟶ CO2(g)+2 H2 O(g)+802 kJ b. Ca(OH)2(s)+65.3 kJ ⟶CaO(s)+H2 O(l) c. 2 Al(s)+Fe2 O3(s) ⟶Al2 O3(s)+2 Fe(l)+850 kJ

    Classify each of the following as exothermic or endothermic and give the $\Delta H$ for each:
a. $\mathrm{CH}_{4}(\mathrm{~g})+2 \mathrm{O}_{2}(\mathrm{~g}) \stackrel{\Delta}{\longrightarrow} \mathrm{CO}_{2}(g)+2 \mathrm{H}_{2} \mathrm{O}(g)+802 \mathrm{~kJ}$
b. $\mathrm{Ca}(\mathrm{OH})_{2}(s)+65.3 \mathrm{~kJ} \longrightarrow \mathrm{CaO}(s)+\mathrm{H}_{2} \mathrm{O}(l)$
c. $2 \mathrm{Al}(s)+\mathrm{Fe}_{2} \mathrm{O}_{3}(s) \longrightarrow \mathrm{Al}_{2} \mathrm{O}_{3}(s)+2 \mathrm{Fe}(l)+850 \mathrm{~kJ}$

General, Organic, Biological Chemistry: Structures of Life

Karen C. Timberlake 5th Edition

Chapter 7, Problem 91

Instant Answer

Solved by Expert Nicole Smina

02/21/2022

Step 1

If heat is released, it's exothermic and the heat is on the right as a product. If heat is absorbed, it's endothermic and the heat is on the left as a reactant. Show more…

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Classify each of the following as exothermic or endothermic and give the $\Delta H$ for each: a. $\mathrm{CH}_{4}(\mathrm{~g})+2 \mathrm{O}_{2}(\mathrm{~g}) \stackrel{\Delta}{\longrightarrow} \mathrm{CO}_{2}(g)+2 \mathrm{H}_{2} \mathrm{O}(g)+802 \mathrm{~kJ}$ b. $\mathrm{Ca}(\mathrm{OH})_{2}(s)+65.3 \mathrm{~kJ} \longrightarrow \mathrm{CaO}(s)+\mathrm{H}_{2} \mathrm{O}(l)$ c. $2 \mathrm{Al}(s)+\mathrm{Fe}_{2} \mathrm{O}_{3}(s) \longrightarrow \mathrm{Al}_{2} \mathrm{O}_{3}(s)+2 \mathrm{Fe}(l)+850 \mathrm{~kJ}$

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Key Concepts

Exothermic Reaction

An exothermic reaction is one in which energy is released to the surroundings, usually in the form of heat. In these reactions, the products have lower enthalpy compared to the reactants, and the change in enthalpy (?H) is negative, reflecting the net loss of energy from the system.

Endothermic Reaction

An endothermic reaction absorbs energy from its surroundings, causing the reaction system to gain heat. This results in products that have higher enthalpy than the reactants, and the overall enthalpy change (?H) is positive, indicating that energy is taken into the system.

Enthalpy Change (?H)

Enthalpy change (?H) is a thermodynamic quantity used to measure the heat exchanged during a chemical reaction at constant pressure. The sign of ?H provides insight into the energy flow of the reaction: a negative ?H signals an exothermic process (energy released), whereas a positive ?H indicates an endothermic process (energy absorbed).

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