/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 59 Are exothermic reactions spontan... [FREE SOLUTION] | 91影视

91影视

Log out

Learning Materials

Features

Discover

Chapter 12: Problem 59

Are exothermic reactions spontaneous only at low temperature? Explain your answer.

Short Answer

Expert verified
Explain why or why not. Answer: No, exothermic reactions are not always spontaneous at low temperatures. The spontaneity of an exothermic reaction depends on the balance between enthalpy change (螖H) and entropy change (螖S), as well as temperature. A reaction is spontaneous when its Gibbs Free Energy (螖G) is negative. An exothermic reaction can be spontaneous at both low and high temperatures if the combined effects of enthalpy (螖H) and entropy (螖S) are favorable.

Step by step solution

01

Understanding exothermic reactions

An exothermic reaction is a type of chemical reaction that releases energy in the form of heat. In these reactions, the total energy of the products is lower than that of the reactants, resulting in a negative enthalpy change.
02

Understanding reaction spontaneity

A spontaneous reaction is one that occurs without any external influence, such as a catalyst or added energy. Spontaneous reactions typically occur when the products are at a lower energy state than the reactants. The Gibbs Free Energy (螖G) is used to determine the spontaneity of a reaction and is described by the following equation: 螖G = 螖H - T螖S, where 螖H is the change in enthalpy, T is the temperature in Kelvin, and 螖S is the change in entropy of the system. A reaction is spontaneous when 螖G is negative.
03

Examining the relation between Gibbs Free Energy and temperature

By analyzing the equation 螖G = 螖H - T螖S, we can understand the effect of temperature on the spontaneity of a reaction. In an exothermic reaction, 螖H is negative, so the term 螖H - T螖S will be negative if the second term, -T螖S, is smaller in magnitude than 螖H or positive if it's larger in magnitude. When T is low, the term -T螖S is smaller, making the Gibbs Free Energy more likely to be negative, suggesting the exothermic reaction is likely to be spontaneous at low temperatures.
04

Considering the effect of entropy on reaction spontaneity

However, the entropy change (螖S) also plays a significant role in determining spontaneity. In a reaction with a positive 螖S, the entropy of the system increases, favoring spontaneity. In contrast, a negative 螖S denotes a decrease in entropy and usually opposes spontaneity. Therefore, the spontaneity of an exothermic reaction at different temperatures depends on the interplay between 螖H and 螖S.
05

Final conclusion

It's not accurate to say that exothermic reactions are spontaneous only at low temperatures. The spontaneity of exothermic reactions depends on the balance between enthalpy change (螖H) and entropy change (螖S), as well as temperature. An exothermic reaction can be spontaneous at both low and high temperatures if the combined effects of enthalpy and entropy are favorable.

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.

Over 30 million students worldwide already upgrade their learning with 91影视!

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

Use the appropriate \(\Delta G_{f}^{\circ}\) data in Appendix 4 to calculate \(\Delta G_{\mathrm{rxn}}^{\circ}\) for the complete combustion of methanol: $$2 \mathrm{CH}_{3} \mathrm{OH}(g)+3 \mathrm{O}_{2}(g) \rightarrow 2 \mathrm{CO}_{2}(g)+4 \mathrm{H}_{2} \mathrm{O}(g)$$

Do decomposition reactions tend to have \(\Delta S_{\mathrm{rxn}}^{\circ}\) values that are greater than zero or less than zero? Why?

Which of the following combinations of entropy changes for a process are mathematically possible? a. \(\Delta S_{\text {sys }}>0, \Delta S_{\text {surr }}>0, \Delta S_{\text {univ }}>0\) b. \(\Delta S_{\text {sys }}>0, \Delta S_{\text {surr }}<0, \Delta S_{\text {univ }}>0\) c. \(\Delta S_{\text {sys }}>0, \Delta S_{\text {surr }}>0, \Delta S_{\text {univ }}<0\)

Calculate the free-energy change for the dissolution in water of one mole of \(\mathrm{NaBr}\) and one mole of \(\mathrm{NaI}\) at \(298 \mathrm{K}\) from the values in the following table. $$\begin{array}{lcc}\hline & \Delta H_{\text {solution }}^{\circ}(\mathrm{k} J / \mathrm{mol}) & \Delta S_{\text {solution }}^{\circ}[J /(\mathrm{mol} \cdot \mathrm{K})] \\\\\text { NaBr } & -0.60 & 57 \\\\\hline \text { Nal } & -7.5 & 74 \\\\\hline\end{array}$$

Which of the following processes is/are spontaneous? a. A tornado forms. b. A broken cell phone fixes itself. c. You get an \(A\) in this course. d. Hot soup gets cold before it is served.
See all solutions

Recommended explanations on Chemistry Textbooks

Physical Chemistry

Read Explanation

Chemistry Branches

Read Explanation

Ionic and Molecular Compounds

Read Explanation

Making Measurements

Read Explanation

Kinetics

Read Explanation

Organic Chemistry

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.