{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}


CHEM31PracticeProblemsCh10 - a values(b From the equation...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
CHEM 31 Additional Practice Problems Free Energy, Equilibrium, and Spontaneity I. (Combining free energy, equilibrium, and kinetics) Consider the reaction: 2NO (g) + O 2 (g) 2NO 2 (g) Thermochemical Information (at 298K): G o f (kJ/mol) H o f (kJ/mol) S o (J/K mol) NO 86.7 90.4 210.6 O 2 0 0 205.0 NO 2 51.8 33.85 240.46 a. The forward rate constant for the above reaction is 7.1x10 9 M -2 s -1 at 25 o C. Assuming a simple one-step mechanism, what is the rate constant for the reverse reaction? (Hint: first find K eq at 25 o C and then find k -1 .) b. What is K for the above reaction at 500K assuming H o f and S o are temperature independent?
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
II. (Combining Free Energy, equilibrium, and acid-base chemistry.) Consider two carboxylic acids (acids that contain the –COOH group): CH 3 COOH (acetic acid, K a = 1.8 x 10 -5 ) and CH 2 ClCOOH (chloroacetic acid, K a = 1.4 x 10 -3 ). (a) Calculate Δ Gº for the ionization of these acids at 25ºC using the K
Background image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: a values. (b) From the equation Δ Gº = Δ Hº – T Δ Sº, we see that the contributions to the Δ Gº term are an enthalpy term ( Δ Hº) and a temperature times entropy term (T Δ Sº). These contributions are listed below for the two acids: Which is the dominant term in determining the value of Δ Gº (and hence K a of the acid)? (c) What processes contribute to Δ Hº? (Consider the ionization of the acids as a Bronsted acid-base reaction and think about bonds that are broken and formed.) (d) Propose a reason why T Δ Sº is more negative for CH 3 COOH. (Hint: ions in aqueous solutions have a tendency to order the dipolar water molecules surrounding them, with the extent of the ordering being greater for smaller ions.) Δ Hº (kJ) T Δ Sº (kJ) CH 3 COOH -0.57 -27.6 CH 2 ClOOH -4.7 -21.1...
View Full Document

{[ snackBarMessage ]}

Page1 / 2

CHEM31PracticeProblemsCh10 - a values(b From the equation...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon bookmark
Ask a homework question - tutors are online