A Calculate E cell - for the following reaction at 298 K -2 Cr s -3 Fe 2-0-01 M - 2 Cr 3-0-01 M -3 Fe s Given - E cell -0-261 Vb Using the E- values of A and B- predict which one is better for coating the surface of iron -E0F e2- - F e-0-44 V- to prevent corrosion and why-Given- E - A 2- - A -2-37 V -E - B 2- - B -0-14 V

(a) 2Cr(s) + 3Fe^2+ (0.01 M) → 2Cr^3+ (0.01 M) + 3Fe(s) n=6 Q= [Cr^3+]^2× 1^3/1^2× [Fe^2+]^3 Q= (0.01)^2× 1/(0.01)^3× 1 = 100/1 Q= 10^2 Using Nernst equation ...

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Byju's Answer

Standard XII

Physics

Speed of Efflux

a Calculate E...

Question

(a) Calculate $E_{c e l l}^{\circ}$ for the following reaction at 298 K:
$2 C r (s) + 3 F e^{2 +} (0.01 M) \to 2 C r^{3 +} (0.01 M) + 3 F e (s)$
Given : $E_{c e l l} = 0.261 V$

(b) Using the $E^{\circ}$ values of A and B, predict which one is better for coating the surface of iron $[E^{o} (F e^{2 +} / F e) = - 0.44 V]$ to prevent corrosion and why?

Given: $E^{\circ} (A^{2 +} / A) = - 2.37 V$ :
$E^{\circ} (B^{2 +} / B) = - 0.14 V$

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Solution

(a) $2 C r (s) + 3 F e^{2 +} (0.01 M) \to 2 C r^{3 +} (0.01 M) + 3 F e (s)$
n=6
$Q = \frac{[C r^{3 +}]^{2} \times 1^{3}}{1^{2} \times [F e^{2 +}]^{3}}$
$Q = \frac{(0.01)^{2} \times 1}{(0.01)^{3} \times 1} = \frac{100}{1}$
$Q = 10^{2}$

Using Nernst equation
$E = E^{\circ} - \frac{0.059}{n} l o g Q$
$E_{c e l l}^{\circ} = E_{c e l l} + \frac{0.059}{n} l o g Q$
$E_{c e l l}^{\circ} = 0.261 + \frac{0.059}{6} \times l o g 10^{2}$
$E_{c e l l}^{\circ} = 0.261 + \frac{0.059}{3}$
$E_{c e l l}^{\circ} = 0.2806$
$E_{c e l l}^{\circ} = 0.281$ (approx)

(b) The metal which is most often used for covering iron with active metal is A because $E^{\circ}$ value of A is more negative.

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Similar questions

Q. (a) Calculate

E_{c e l l}^{\circ}

for the following reaction at 298 K:

2 C r (s) + 3 F e^{2 +} (0.01 M) \to 2 C r^{3 +} (0.01 M) + 3 F e (s)

Given :

E_{c e l l} = 0.261 V

(b) Using the

E^{\circ}

values of A and B, predict which one is better for coating the surface of iron

[E^{o} (F e^{2 +} / F e) = - 0.44 V]

to prevent corrosion and why?

Given:

E^{\circ} (A^{2 +} / A) = - 2.37 V

E^{\circ} (B^{2 +} / B) = - 0.14 V

Q. Calculate e.m.f of the following cell at

298 K

2 C r (s) + 3 {F e}^{2 +} (0.1 M) \to 2 {C r}^{3 +} (0.01 M) + 3 F e (s)

Given:

E ({C r}^{3 +} | C r) = - 0.74 V E ({F e}^{2 +} | F e) = - 0.44 V

Q. Calculate

E_{c e l l}

for :

F e_{(} s) | F e^{2 +} (0.1 M) | | F e^{3 +} (0.01 M) | F e^{2 +} (1 M) | P t

, T = 298 K.
Given

E_{F e^{3 +} / F e^{2 +}}^{0} = + 0.771 V, E_{F e^{2 +} / F e}^{0} = - 0.41 V

Q. Calculate the value of

E_{c e l l}

298 K

for the following cell:

A l / A l^{3 +} (0.01 M) ∥ S n^{2 +} (0.015 M) / S n

E_{A l^{3 +} / A l}^{0} = - 1.66 v o l t

and

E_{S n^{2 +} / S n}^{0} = - 0.14 v o l t

Q. The equilibrium constant for the reaction given below at 298 K is if

E_{c e l l} = 0.2905 V

at 298 K is:

Z n (s) + F e^{2 +} (a q) 0.01 M \to Z n^{2 +} 0.1 M (a q) + F e (s)

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