Ch.6 - Thermochemistry See 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

Enthalpy of Formation

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

Solution: Consider 0.0110 moles of HCl consumed in the chemical reaction at standard temperature and pressure: 2 HCl (aq) + Mg (s) → MgCl2 (aq) + H2 (g) ΔHf° (HCl) = −167.2 kJ;  ΔH f° (MgCl2) = −801.2 kJ   Identify the statements below as either true or false.   Magnesium is undergoing oxidation. Mg has the most protons of any atom in the reaction. The reaction will form 0.123 L of H 2 gas. The reaction will also consume 0.134 g of Mg. The ΔH of the reaction cannot be calculated. The energy change from the reaction, q rxn = −2.57 kJ.

Problem

Consider 0.0110 moles of HCl consumed in the chemical reaction at standard temperature and pressure:

2 HCl (aq) + Mg (s) → MgCl2 (aq) + H2 (g)

ΔHf° (HCl) = −167.2 kJ;  ΔH f° (MgCl2) = −801.2 kJ

 

Identify the statements below as either true or false.

 

Magnesium is undergoing oxidation.

Mg has the most protons of any atom in the reaction.

The reaction will form 0.123 L of H 2 gas.

The reaction will also consume 0.134 g of Mg.

The ΔH of the reaction cannot be calculated.

The energy change from the reaction, q rxn = −2.57 kJ.