Electrochemistry Test

Question 1
1 / -0

The standard reduction potential data at 25$$^o$$C is given below:
$$E^o (Fe^{3+} , Fe^{2+}) = +0.77 V$$;
$$E^o (Fe^{2+} , Fe) = -0.44 V$$
$$E^o(Cu^{2+}, Cu) = +0.34 V$$;
$$E^o(Cu^+ , Cu) = +0.52 V$$
$$E^o (O_2(g) + 4H^+ + 4e^- \rightarrow 2H_2O ] = + 1.23 V$$;
$$E^o (O_2 (g) + 2H_2 O + 4e^- \rightarrow 4OH^-) = + 0.40 V$$
$$E^o (Cr^{3+} , Cr) = - 0.74 V$$;
$$E^o (Cr^{2+} , Cr) = - 0.91 V$$;
Match $$E^o$$ of the redox pair in List I with the values given in List II and select the correct answer using the code given below the lists.
List I List II
(P) $$E^o (Fe^{3+}, Fe)$$ (1) -0.18 V
(Q) $$E^o (4H_2O \rightleftharpoons 4H^+ + 4OH^-)$$ (2) -0.4 V
(R) $$E^o (Cu^{2+} + Cu \rightarrow 2 Cu^+)$$ (3) 0.04 V
(S) $$E^o(Cr^{3+}, Cr^{2+})$$ (4) -0.83 V

A
$$P-4, Q-1, R-2, S-3$$

B
$$P-2, Q-3, R-4, S-1$$

C
$$P-1, Q-2, R-3, S-4$$

D
$$P-3, Q-4, R-1, S-2$$

Question 2
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The standard reduction potentials $$E^{\circleddash}$$ for the half reactions are follows :

$$Zn\, \rightarrow\, Zn^{2+}\, +\, 2e^{-};\, \quad\, E^{\circleddash}\, =\, +0.76\, V$$
$$Fe\, \rightarrow\, Fe^{2+}\, +\, 2e^{-};\, \quad\, E^{\circleddash}\, =\, 0.41\, V$$

The EMF for the cell reaction $$Fe^{2+}\, Zn\, \rightarrow\, Zn^{2+}\, +\, Fe$$ is:

A
$$- 0.35 V$$

B
$$+ 0.35 V$$

C
$$+ 1.17 V$$

D
$$- 1.17 V$$

Question 3
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For the reaction :
$$4Al(s)\, +\, 3O_{2}(g)\, +\, 6H_{2}O\, +\, 4\, \overset{\ominus}{O}H\, \rightarrow\, 4[Al(OH)_{4}]^{\oplus}$$
$$E^{\ominus}_{cell}\, =\, 2.73\, V$$
If $$\Delta_{f}G^{\ominus}\, [\overset{\oplus}{O}H]\, =\, -\, 157\, kJ\, mol^{-1}$$;
$$\Delta_{f}G^{\ominus}\, (H_{2}O)\, =\, -\, 237.2\, kJ\, mol^{-1}$$.
The value of $$\Delta_{f}G^{\ominus}\, [Al(OH)_{4}]^{\ominus}$$ is:
[free energy of formation of $$(Al(OH)_{4}^{\ominus}]$$.

A
$$\Delta_{f}G^{\ominus}[Al(OH)_{4}]^{\ominus}\, =\, + 3.50\, \times\, 10^{3}\, kJ\, mol^{-1}$$

B
$$\Delta_{f}G^{\ominus}[Al(OH)_{4}]^{\ominus}\, =\, + 2.40\, \times\, 10^{3}\, kJ\, mol^{-1}$$

C
$$\Delta_{f}G^{\ominus}[Al(OH)_{4}]^{\ominus}\, =\, - 1.30\, \times\, 10^{3}\, kJ\, mol^{-1}$$

D
$$None \:\:of \:\:these $$

Question 4

1 / -0

An aqueous solution of X is added slowly to an aqueous solution of Y as shown in List I. The variation in conductivity of theses reactions is given in List II. Match List I with List II and select the correct using the code given below the lists:

List-A	List-B
(P) $$\underset {X}{(C_2H_5)_3N}+\underset {Y}{CH_2COOH}$$	(1) Conductivity decreases and then increases
(Q) $$\underset {X}{KI(0.1M)}+\underset {Y}{AgNO_3(0.01M)}$$	(2) Conductivity decreases and then does not change much
(R) $$\underset {X}{CH_2COO}+\underset {Y}{KOH}$$	(3) Conductivity increases and then does not change much
(S) $$\underset {X}{NaOH}+\underset {Y}{HI}$$	(4) Conductivity does not change much and then increases.

3, 4, 2, 1

4, 3, 2, 1

2, 3, 4, 1

1, 4, 3, 2

Question 5
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Which of the following is used as electrodes in batteries?

A
Diamond

B
Graphite

C
Activated charcoal

D
Carbon black

Question 6
1 / -0

Directions For Questions

The standard reduction potentials of some half reactions are given as below
$$Cu^{2+} + e \rightarrow Cu^+; E^o_1 = 0.15 V$$
$$Cu^{+} + e \rightarrow Cu; E^o_2 = 0.5 V$$
$$Ag^{+} + e \rightarrow Ag; E^o_3 = 0.799 V$$
The decrease in Gibbs energy $$(- \Delta G) $$ is responsible for the production of equivalent amount of electrical work. Thus, $$- \Delta G = n F \times E$$

...view full instructions

The $$E^o_{cell} $$ for $$Cu | Cu^{2+}$$ in volt is:

A
$$0.35$$

B
$$-0.35$$

C
$$+0.325$$

D
$$-0.325$$

Question 7
1 / -0

Separating the components of a homogeneous mixture using electricity is called:

A
electrification

B
electrolysis

C
electrolyte

D
electromagnetisation

Question 8
1 / -0

For the electrolytic production of $$NaClO_4$$ from $$NaClO_3$$ according to the reaction $$NaClO_3 + H_2O \rightarrow NaClO_4 + H_2$$. How many faradays of electricity would be required to produce 0.5 mole of $$NaClO_4$$ ?

A
$$1$$

B
$$2$$

C
$$3$$

D
$$1.5$$

Question 9
1 / -0

Chromium plating can involve the electrolysis of an electrolyte of an acidified mixture of chromic acid and chromium sulphate. If during electrolysis the article being plated increases in mass by 2.6 g and $$0.6\, dm^{3}$$ of oxygen are evolved at an inert anode, the oxidation state of chromiumions being discharged must be : (assuming atomic weight of Cr = 52 and 1 mole of gas at room temperature and pressure occupies a volume of 24 $$dm^{3}$$)

A
$$-1$$

B
$$0$$

C
$$+1$$

D
$$+2$$

Question 10
1 / -0

The passage of $$1.5$$ Faradays of electricity corresponds to the flow of how many electrons?

A
$$6\times {10}^{23}$$

B
$$9\times {10}^{23}$$

C
$$12\times {10}^{23}$$

D
$$3\times {10}^{23}$$

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Electrochemistr...

Question 1

$$P-4, Q-1, R-2, S-3$$

$$P-2, Q-3, R-4, S-1$$

$$P-1, Q-2, R-3, S-4$$

$$P-3, Q-4, R-1, S-2$$

Question 2

$$- 0.35 V$$

$$+ 0.35 V$$

$$+ 1.17 V$$

$$- 1.17 V$$

Question 3

$$\Delta_{f}G^{\ominus}[Al(OH)_{4}]^{\ominus}\, =\, + 3.50\, \times\, 10^{3}\, kJ\, mol^{-1}$$

$$\Delta_{f}G^{\ominus}[Al(OH)_{4}]^{\ominus}\, =\, + 2.40\, \times\, 10^{3}\, kJ\, mol^{-1}$$

$$\Delta_{f}G^{\ominus}[Al(OH)_{4}]^{\ominus}\, =\, - 1.30\, \times\, 10^{3}\, kJ\, mol^{-1}$$

$$None \:\:of \:\:these $$

Question 4

3, 4, 2, 1

4, 3, 2, 1

2, 3, 4, 1

1, 4, 3, 2

Question 5

Diamond

Graphite

Activated charcoal

Carbon black

Question 6

$$0.35$$

$$-0.35$$

$$+0.325$$

$$-0.325$$

Question 7

electrification

electrolysis

electrolyte

electromagnetisation

Question 8

$$1$$

$$2$$

$$3$$

$$1.5$$

Question 9

$$-1$$

$$0$$

$$+1$$

$$+2$$

Question 10

$$6\times {10}^{23}$$

$$9\times {10}^{23}$$

$$12\times {10}^{23}$$

$$3\times {10}^{23}$$

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