Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 6: Problem 67

The standard enthalpy change \(\Delta H^{\circ}\) for the thermal decomposition of silver nitrate according to the following equation is \(+78.67 \mathrm{~kJ}\) : $$ \mathrm{AgNO}_{3}(s) \longrightarrow \mathrm{AgNO}_{2}(s)+\frac{1}{2} \mathrm{O}_{2}(g) $$ The standard enthalpy of formation of \(\mathrm{AgNO}_{3}(s)\) is \(-123.02 \mathrm{~kJ} / \mathrm{mol}\). Calculate the standard enthalpy of formation of \(\mathrm{AgNO}_{2}(s)\).

Short Answer

Expert verified
The standard enthalpy of formation of AgNO2 is -44.35 kJ/mol.

Step by step solution

01

Calculating the Standard Enthalpy

From the given chemical reaction, \(\mathrm{AgNO}_{3}(s) \longrightarrow \mathrm{AgNO}_{2}(s)+\frac{1}{2}\mathrm{O}_{2}(g)\), we know that the standard enthalpy change ΔH° for this reaction is +78.67 kJ. This means that the process of transforming AgNO3 to AgNO2 and O2 absorbs 78.67 kJ of heat.
02

Using Hess's Law

According to Hess's Law, the enthalpy change of a chemical reaction depends only on the initial and final states, not on the path taken. So, we can say that the enthalpy of the reaction (±ΔH° of reaction) is the sum of the enthalpies of formation of the products minus the sum of the enthalpies of formation of the reactants.
03

Formulating the equation and solving

This implies that \(ΔH^{\circ} of ~Reaction = Σf \Delta H^{\circ}_products - Σf \Delta H^{\circ}_reactants\). If we apply this to our problem, we swap the equation to solve for the enthalpy of formation of AgNO2:\(f \Delta H^{\circ}_{AgNO2} = ΔH^{\circ}_reaction + f \Delta H^{\circ}_{AgNO3}\). Now plug in the values:\(f \Delta H^{\circ}_{AgNO2} = +78.67 ~kJ/mol + (-123.02 ~kJ/mol)\)

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Calculate the internal energy of a Goodyear blimp filled with helium gas at \(1.2 \times 10^{5} \mathrm{~Pa}\). The volume of the blimp is \(5.5 \times 10^{3} \mathrm{~m}^{3} .\) If all the energy were used to heat 10.0 tons of copper at \(21^{\circ} \mathrm{C},\) calculate the final temperature of the metal. (Hint: See Section 5.6 for help in calculating the internal energy of a gas. 1 ton \(\left.=9.072 \times 10^{5} \mathrm{~g} .\right)\)

Why are cold, damp air and hot, humid air more uncomfortable than dry air at the same temperatures? (The specific heats of water vapor and air are approximately \(1.9 \mathrm{~J} / \mathrm{g} \cdot{ }^{\circ} \mathrm{C}\) and \(1.0 \mathrm{~J} / \mathrm{g} \cdot{ }^{\circ} \mathrm{C}\), respectively.

Define calorimetry and describe two commonly used calorimeters. In a calorimetric measurement, why is it important that we know the heat capacity of the calorimeter? How is this value determined?

Portable hot packs are available for skiers and people engaged in other outdoor activities in a cold climate. The air-permeable paper packet contains a mixture of powdered iron, sodium chloride, and other components, all moistened by a little water. The exothermic reaction that produces the heat is a very common one- the rusting of iron: $$ 4 \mathrm{Fe}(s)+3 \mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{Fe}_{2} \mathrm{O}_{3}(s) $$ When the outside plastic envelope is removed, \(\mathrm{O}_{2}\) molecules penetrate the paper, causing the reaction to begin. A typical packet contains \(250 \mathrm{~g}\) of iron to warm your hands or feet for up to \(4 \mathrm{~h}\). How much heat (in \(\mathrm{kJ}\) ) is produced by this reaction? (Hint: See Appendix 2 for \(\Delta H_{\mathrm{f}}^{\circ}\) values.

(a) For most efficient use, refrigerator freezer compartments should be fully packed with food. What is the thermochemical basis for this recommendation? (b) Starting at the same temperature, tea and coffee remain hot longer in a thermal flask than chicken noodle soup. Explain.
See all solutions

Recommended explanations on Chemistry Textbooks

Kinetics

Read Explanation

Physical Chemistry

Read Explanation

Organic Chemistry

Read Explanation

Chemical Reactions

Read Explanation

Inorganic Chemistry

Read Explanation

Chemistry Branches

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free