Electrochemistry Test

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Electrochemistry Test - 41

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Weekly Quiz Competition

Question 1
1 / -0

What is the difference between galvanic cell and electrolytic cell?

A
In galvanic cell, electrical energy is produced while in electrolytic cell electrical energy is consumed

B
In galvanic cell, anode is $$(-)$$ ve while in electrolytic cell anode is $$(+)$$ ve

C
In galvanic cell, cathode is $$(+)\ ve$$ while in electrolytic cell anode is $$(-)\ ve$$

D
All are correct

Solution

In a galvanic cell, electrical energy is produced by chemical reactions and cathode is $$(+)$$ charged and anode is $$(-)$$ charged.

In an electrolytic cell, electrical energy is consumed to carry out the chemical reactions and the cathode is $$(-)$$ charged and the anode is $$(+)$$ charged.
Question 2
1 / -0

During the electrolysis of $$AgNO_{3}$$ (using $$Pt$$ electrodes) concentration around cathode as well as anode falls from $$4M$$ to $$3M$$. What will happen if this happened with $$Ag$$ electrodes?

A
Result will remain same

B
Concentration around cathode will fall from $$4M$$ to $$3M$$ but around anode will increase from $$4M$$ to $$5M$$

C
Reverse of statement (b)

D
Concentration increases from $$4M$$ to $$5M$$ on both the electrodes

Solution
Question 3
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Use of electrolysis is not done in _____________.

A
production of $$Na$$

B
production of water

C
purification of metal

D
production of $$KOH$$

Solution

Use of electrolysis is not done in the production of water. It is mainly used in obtaining reactive metal.
Question 4
1 / -0

Directions For Questions

In a lead storage battery, $$Pb$$ (anode) and $$PbO_{2}$$ (cathode) are used. Concentrated $$H_{2}SO_{4}$$ is used as electrolyte. The battery holds $$3.5\ litre$$ acid with it. In the discharge process, the density of acid fell from $$1.294$$ to $$1.139\ g/mL$$. The sulphuric acid of density $$1.294\ g\ mL$$ is $$39$$% by mass and that of density $$1.139\ g/mL$$ is $$20$$% by mass.

...view full instructions

The amount of charge which the battery must have been used is:

A
$$9.88\ F$$

B
$$8.98\ F$$

C
$$8.89\ F$$

D
$$7.88\ F$$

Solution

wt. of $$H_2SO_4$$ at initial = 3.5*1000*.39*1.294 = 1766.31 gm
wt. of $$H_2SO_4$$ after decay =3.5*1000*1.3*0.20 = 797.3 gm
amount deposite = 969 gm
n-fector of $$H_2SO_4$$ = 1
w = zQ
Q = 969.0F$$\dfrac{1}{98}$$
Q = 9.88F
Question 5
1 / -0

For a spontaneous reaction $$\Delta {G}^{o}$$ and $${E}^{o}$$ cell will be respectively

A
$$-ve$$ and $$+ve$$

B
$$+ve$$ and $$-ve$$

C
$$+ve$$ and $$+ve$$

D
$$-ve$$ and $$-ve$$

Solution

For a spontaneous reaction, the standard change in Gibbs free energy $$\displaystyle \Delta G^0$$ and the standard cell potential $$\displaystyle E^0_{cell}$$ will be negative and positive respectively.

$$\displaystyle \Delta G^0 < 0 $$
$$\displaystyle E^0_{cell} > 0$$

Note:
$$\displaystyle \Delta G^0 = -nFE^0_{cell}$$

Thus, $$\displaystyle \Delta G^0$$ and $$\displaystyle E^0_{cell}$$ have opposite signs.
Question 6
1 / -0

Pick out the pair in which the energy change of one is reverse of the energy change in the other :
(1) radio (2) fluorescent lamp (3) toaster (4) photoelectric cell

A
1 and 2

B
2 and 3

C
2 and 4

D
3 and 4

Solution

In fluorescent lamp, current is used to generate light and in photoelectric cell, light is used to generate electric current:
hence, the energy change is reverse of the energy change in the other.
Question 7
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Which of the following statements are correct ?

A
1 faraday is the charge of 1 mole electron.

B
1 faraday is used to deposit 1 g equivalent of a substance.

C
5.6 litre $$O_2$$ will be evolved at STP by 1 faraday charge.

D
11.2 litre $$Cl_2$$ will be evolved at SIT by 1 faraday charge.

Solution

The Faraday which is denoted by the symbol F and sometimes is named after Michael Faraday. In physics and chemistry, this constant represents the magnitude of electric charge on one mole of electrons

IF= 96485.33289(59) C\mol
Hence option A is correct.
Question 8
1 / -0

1 C electricity deposits:

A
half of electrochemical equivalent of $$Ag$$

B
electrochemical equivalent of $$Ag$$

C
96500 g of $$Ag$$

D
10.8 g of $$Ag$$

Solution

1 C electricity deposits electrochemical equivalent of $$Ag$$.

Note:
Electrochemical equivalent is the mass of the ion deposited by passing a current of one ampere for one second (i.e, one coulomb).

According to Faraday's first law of electrolysis, the amount of substance that undergoes oxidation or reduction at each electrode during electrolysis is directly proportional to the amount of electricity that passes through the cell.
Question 9
1 / -0

The mass and charge of 1 mole electrons will be:

A
1 kg; 96500 C

B
0.55 mg; 96500 C

C
1.55 mg; 96500 C

D
5.5 mg; 96500 C

Solution
Question 10
1 / -0

In which of the following case, increase on concentration of ion cause increase in $$E_{cell}$$?

A
$$Pt(H_2)H^+(aq)$$

B
$$Pt|Quinhydrone|H^+(aq)$$

C
$$Ag|Ag^+(aq)$$

D
$$Ag, AgCl|Cl^-(aq)$$

Solution

(a) $$\displaystyle\frac{1}{2}H_2(g)\rightarrow H^+(aq)+e^-$$
$$E_{cell}=E^o_{cell}-0.0591$$ log $$[H^+]$$
(c) $$Ag(s)\rightarrow Ag^+(aq)$$
$$E_{cell}=E^o_{cell}-0.0591log[Ag^+]$$
(d) $$Ag(s)+Cl^-(aq)\rightarrow AgCl(s)+e^-$$
$$E_{cell}=E^o_{cell}-0.0591log\displaystyle \frac{1}{[Cl^-]}$$.
Thus, in case(d), the $$E_{cell}$$ increases with increase in the concentration of ions.

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Re-Attempt Weekly Quiz Competition

Electrochemistry Test - 41

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Electrochemistry Test - 41

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Question 1

In galvanic cell, electrical energy is produced while in electrolytic cell electrical energy is consumed

In galvanic cell, anode is $$(-)$$ ve while in electrolytic cell anode is $$(+)$$ ve

In galvanic cell, cathode is $$(+)\ ve$$ while in electrolytic cell anode is $$(-)\ ve$$

All are correct

Solution

Question 2

Result will remain same

Concentration around cathode will fall from $$4M$$ to $$3M$$ but around anode will increase from $$4M$$ to $$5M$$

Reverse of statement (b)

Concentration increases from $$4M$$ to $$5M$$ on both the electrodes

Solution

Question 3

production of $$Na$$

production of water

purification of metal

production of $$KOH$$

Solution

Question 4

$$9.88\ F$$

$$8.98\ F$$

$$8.89\ F$$

$$7.88\ F$$

Solution

Question 5

$$-ve$$ and $$+ve$$

$$+ve$$ and $$-ve$$

$$+ve$$ and $$+ve$$

$$-ve$$ and $$-ve$$

Solution

Question 6

1 and 2

2 and 3

2 and 4

3 and 4

Solution

Question 7

1 faraday is the charge of 1 mole electron.

1 faraday is used to deposit 1 g equivalent of a substance.

5.6 litre $$O_2$$ will be evolved at STP by 1 faraday charge.

11.2 litre $$Cl_2$$ will be evolved at SIT by 1 faraday charge.

Solution

Question 8

half of electrochemical equivalent of $$Ag$$

electrochemical equivalent of $$Ag$$

96500 g of $$Ag$$

10.8 g of $$Ag$$

Solution

Question 9

1 kg; 96500 C

0.55 mg; 96500 C

1.55 mg; 96500 C

5.5 mg; 96500 C

Solution

Question 10

$$Pt(H_2)H^+(aq)$$

$$Pt|Quinhydrone|H^+(aq)$$

$$Ag|Ag^+(aq)$$

$$Ag, AgCl|Cl^-(aq)$$

Solution

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