Chemistry 163 Final Review Give the rate law and overall order tor 2NO_2 rightar

Question

Chemistry 163 Final Review Give the rate law and overall order tor 2NO_2 rightarrow 2NO + O_2 when What is (NO_2) at 125 $ if (NO_2)_0 = 0.015 M ? Calculate the pH of a 0.500 N aqueous solution of HCOOH, k_a = 1.77 Times 10^-4 Given: Au^3+ + 2e rightarrow Au^+ E degree cell = 1.36 V Zn^2+ + 2e^- rightarrow Zn E degree cell = -0.76 V What is the overall balanced equation? What is the cell diagram? What is oxidized? What is the reducing agent? What is the cell potential? What is Delta G? Is the reaction spontaneous?

Explanation / Answer

Q.1:(a): Let the order of the reaction w.r.to NO2 is 'y' and the rate constant be 'k'.

Now rate = kx[NO2]y

7.1x10-5 = k x [0.01]y  ------- (1)

28.1x10-5 = k x [0.02]y  ------- (2)

Dividing eqn(1) and (2)

=> 28.1x10-5 / 7.1x10-5 = (0.02 / 0.01)y

=> 4 = (2)y

=> y = 2.

Hence the reaction is a 2nd order reaction. (answer)

Rate law is

rate = kx[NO2]2  (answer)

where rate constant, k = 7.1x10-5 / (0.01)2 = 0.71 M-1.s-1

Q.2: concentration of H+ for a weak acid can be calculated from the following formulae

[H+] = squareroot(Ka x C) = squareroot(1.77x10-4x0.500) =

=> [H+] = 9.40744x10-3 M

Now pH = - log(9.40744x10-3 M) = 2.03 (answer)

Q.3: (a) Overall balanced equation:

Au3+ + Zn ------ > Au+ + Zn2+

(b) Cell diagram: Zn / Zn2+ // Au3+ / Au+

(c): Zn is oxidized.

(d): Since Zn is oxidized, it is also the reducing agent.

(e): Cell potential, E0(cell) = 1.36 V + 0.76 V = 2.12 V

(f): deltaG = - nFE0(cell) = - 2 x 96500 x 2.12 = - 409164 J = - 409.16 kJ

(g) Since deltaG is negative, the reaction spontaneous

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.