Ch.6 - Thermochemistry WorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds

Endothermic & Exothermic Reactions

See all sections
Sections
Internal Energy
Calorimetry
Thermochemical Equation
Hess's Law
Enthalpy of Formation
End of Chapter 6 Problems
Additional Practice
Units of Energy
Endothermic & Exothermic Reactions
Additional Guides
Enthalpy

Solution: Which one of the following processes is endothermic?a. 2 H2 (g) + O2 (g) → 2 H2O (g)b. H2O (g) → H 2O (l)c. CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (g)d. H2O (s) → H2O (l)e. 2 Al (s) + Fe2O3 (s) → Al2O3

Solution: Which one of the following processes is endothermic?a. 2 H2 (g) + O2 (g) → 2 H2O (g)b. H2O (g) → H 2O (l)c. CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (g)d. H2O (s) → H2O (l)e. 2 Al (s) + Fe2O3 (s) → Al2O3

Problem

Which one of the following processes is endothermic?

a. 2 H2 (g) + O(g) → 2 H2O (g)

b. H2O (g) → H 2O (l)

c. CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (g)

d. H2O (s) → H2O (l)

e. 2 Al (s) + Fe2O3 (s) → Al2O3 (s) + 2 Fe (s)

Solution

We’re being asked to determine which of the following processes is endothermic.


Recall that:

Exothermic reactions

lose energy, releases heat, temperature of the surroundings increases
▪ involves bond formation (for phase change: gas → liquid → solid)
ΔH is negative

Endothermic reactions

gain/requires energy, absorbs heat, temperature of the surroundings decreases
▪ involves breaking bonds (for phase change: solid → liquid → gas)
ΔH is positive


Analyzing process given:

View the complete written solution...