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Consider two carboxylic acids (acids that contain the $-\mathrm{COOH}$ group): $\mathrm{CH}_{3} \mathrm{COOH}$ (acetic acid, $\left.K_{\mathrm{a}}=1.8 \times 10^{-5}\right)$ and $\mathrm{CH}_{2} \mathrm{ClCOOH}$ (chloroacetic acid, $\left.K_{\mathrm{a}}=1.4 \times 10^{-3}\right) .$ (a) Calculate $\Delta G^{\circ}$ for the ionization of these acids at $25^{\circ} \mathrm{C}$. (b) From the equation $\Delta G^{\circ}=\Delta H^{\circ}-T \Delta S^{\circ},$ we see that the contributions to the $\Delta G^{\circ}$ term are an enthalpy term $\left(\Delta H^{\circ}\right)$ and a temperature times entropy term $\left(T \Delta S^{\circ}\right) .$ These contributions are listed below for the two acids: $$\begin{array}{lcc}\hline & \Delta H^{\circ}(\mathrm{kJ} / \mathrm{mol}) & T \Delta S^{\circ}(\mathrm{k} \mathrm{J} / \mathrm{mol}) \\\hline \mathrm{CH}_{3} \mathrm{COOH} & -0.57 & -27.6 \\\mathrm{CH}_{2} \mathrm{ClCOOH} & -4.7 & -21.1 \\\hline\end{array}$$Which is the dominant term in determining the value of $\Delta G^{\circ}$ (and hence $K_{\mathrm{a}}$ of the acid)? (c) What processes contribute to $\Delta H^{\circ} ?$ (Consider the ionization of the acids as a Bronsted acid-base reaction.) (d) Explain why the $T \Delta S^{\circ}$ term is more negative for $\mathrm{CH}_{3} \mathrm{COOH}.$

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a.$$1. 6 \times 10^{3} \mathrm{J} / \mathrm{mol}$$b. TAS$^\circ$ is dominantc. The breaking of OH bond in ionizing & finding OH bond in $$4_{30}^{+}$$d. More disordered in CH$_3$CLOO - & more ordered in CH$_3$COO-

Chemistry 102

Chapter 17

Entropy, Free Energy, and Equilibrium

Thermodynamics

University of Central Florida

University of Kentucky

Lectures

00:42

In thermodynamics, the zeroth law of thermodynamics states that if two systems are in thermal equilibrium with a third system, they are also in thermal equilibrium with each other.

01:47

A spontaneous process is one in which the total entropy of the universe increases. In a spontaneous process, the system will move from an ordered state to a disordered state, such as from ice to water, or from a solid to a gas. The concept of spontaneity was introduced by Rudolf Clausius in 1850.

05:09

Consider two carboxylic ac…

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Given : Enthalpy of ioniza…

07:20

Estimate the ionization co…

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At $25^{\circ} \mathrm{C}$…

02:45

Malonic acid has two carbo…

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Acetic acid, $\mathrm{CH}_…

02:04

On the basis of $\Delta G^…

solution for the above question solution forward A we have dealt touchy note is equal to minus rt needle. Okay, And here K is equal to 1.8. Multiply generous to the power minus five and tear by putting values 8.31 for multiply 298 Nature lock 1.8 Multiply generous to devour. Minus five is equal to 2.7. Multiply 10 Dressed to the power four. Sure per vote on Delta Jeannot is equal to minus rt needle. Okay, And here K off. See? It's too C l c The below edge is ableto 1.4 multiplied tenders to dip our minus three Musical True. Yeah. Minus 8.31 for multiply 298 Multiply needs a lock into 1.4. Multiply 10 ways to devour minus three visible to 1.6 multiplied and rest to devour. Four. Jewel Permal solution for part B. The Delta isnot is dominant and answer for Parsi The breaking off or it bond in Are you ny zing Ionizing are forming all right or its bond. Mm. Is three or positive? Principal party more disordered in CS three c developed C l. Okay. See the bell? Oh, minus and more ordered. Hmm. C is three c double o negative because she is three c the balloon negative piece similar.

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