Electrolytic Cell

Q.

When 9.65 coulombs of electricity is passed through a solution of silver nitrate (atomic weight of Ag = 107.3, approximately 108) the amount of silver deposited is:

1. 16.2 mg
2. 10.8 mg
3. 21.2 mg
4. 5.4 mg

Q.

The standard hydrogen electrode has zero electrode potential because

1. Hydrogen is the easiest to oxidize

2. This electrode potential is assumed to be zero

3. Hydrogen atom has only one electron

4. Hydrogen is the lightest element

Q.

(a) Give reason: The electrolysis of acidulated water is considered to be an example of catalysis.

(b) During the electrolysis of copper [II] sulphate solution using platinum as cathode and carbon as anode

(i) State what you observe at the cathode and at the anode

(ii) State the change noticed in the electrolyte

(iii) Write the reactions at the cathode and at the anode.

(c) Differentiate between electrical conductivity of --- copper sulphate solution and of copper metal.

Q.

A.C. current is used for electroplating.

1. True

2. False

Q.

(a) Here is an electrode reaction :

$Cu\to C{u}^{2+}+2e^{-}$. At which electrode (anode or cathode) would such a reaction take place? Is this an example of oxidation or reduction ?

(b) A solution contains magnesium ions $\left(M{g}^{2+}\right)$, iron (II) ions $F{e}^{2+}$ and copper ions $C{u}^{2+}$. On passing an electric current through this solution, which ions will be the first to be discharged at the cathode? Write the equation for the cathode reaction.

(c) Why is carbon tetrachloride, which is a liquid, a non-electrolyte ?

(d) During the electrolysis of molten lead bromide, which of the following takes place ?

A. Bromine is released at the cathode,

B. Lead is deposited at the anode,

C. Bromine ions gain electrons,

D. Lead is deposited at the cathode.

Q.

(a) Write two points of difference between electric energy and electric power (b) Out of $60\mathrm{w}$ and $40\mathrm{w}$ lamps which one has higher electrical resistance when in use?

Q. During electrolysis of copper, copper gets deposited on the _______________.

1. anode
2. cathode
3. electrolyte
4. surface of the container

Q. What does a negative e.m.f. for a cell indicate ?

1. Electrons flow through the external circuit in the reverse direction.

2. The opposite half-cell reactions take place spontaneously.

3. The reactions as written are not spontanceous

4. All of the above.

Q.

Why are redox reactions used in batteries?

Q.

Give a reason for the following

In the electrolysis of acidified water, dilute sulphuric acid is preffered to dilute nitric acid for acidification.

Q.

Why are different products obtained when molten $MgC{l}_2$ and aqueous $MgC{l}_2$ are electrolysed with inert electrodes?

Q.

How can you experimentally demonstrate that cathode rays are negatively charged particles?

Q.

Name a non-metallic element which is a conductor of electricity.

Q. Write the equations for the reactions, which take place at the electrodes during the electrolysis of lead bromide.

Q.

Give reason:

Metals displace Hydrogen from its acids, whereas non-metals do not.

Q.

During electrolytic dissociation of sodium chloride, the sodium ions are discharged at the cathode. Give reasons.

Q. Which of the following statements are true regarding the electroplating an iron key with copper?

1. Iron is connected to the negative terminal of the battery.
2. Copper is connected to the positive terminal of the battery.
3. Copper sulphate solution is used as the electrolyte.
4. Sulphuric acid is used as the electrolyte.

Q. Fill in the blanks by selecting the option with the correct words.
The process of removing impurities from impure metal to obtain pure metal is known as ______ of metal. The most widely used method for refining is ______. In this method, the impure metal is taken as ______ and the pure metal is taken as ______.

1. Refining, electrolytic refining, anode, cathode
2. Calcination, electrolysis, cathode, anode
3. Refining, electrolytic refining, cathode, anode
4. Refining, smelting, cathode, anode

Q.

On electrolysis of $CuS{O}_4$ solution in presence of platinum, the solution becomes colorless. Why?

Q. One of the most successful fuel cell uses the reaction of hydrogen with oxygen to form water. The cell was used for providing electrical power in the Apollo space program. The water vapors produced during the reaction were condensed and added to the drinking water supply for the astronauts. In the cell, hydrogen and oxygen are bubbled through porous carbon electrodes into concentrated aqueous sodium hydroxide solution. Which of the following can be used as catalysts in order to increase the rate of electrode reactions in this fuel cell?

1. Lithium
2. Palladium
3. All of above
4. Titanium

Q.

Element X is a metal with a valency 2. Element Y is a non-metal with a valency 3.

(a) Write equations to show how X and Y form ions?

(b) If Y is a diatomic gas, write the equation for the direct combination of X and Y to form a compound.

(c) If the compound formed between X and Y is melted and an electric current passed through the molten compound, the element X will be obtained at the ___ and Y at the ___ of the electrolytic cell.

(Provide the missing words).

Q.

An electrode connected to the negative terminal of a voltage source is called the anode.

1. True
2. False

Q.

If the compound formed between Y and X is melted and an electricity is passed through the compound, the element X will be obtained at the ________

and Y at the __________- of the electrolytic cell.

Q.

Copy and complete the following table which refers to the conversion of ions to neutral particles.

Conversion	Ionic equation	Oxidation/ reduction
Chloride ion to chlorine molecule	………………………….	…………………………………….
Lead (II) ion to lead	………………………………..	……………………………………

Q.

A slow current for a longer time should be used for electroplating.

1. True

2. False

Q.

Explain why Calcium does not occur free in nature.

Q. 15. What are material particles and explain ionisation.

Q.

Is metals attract cathode electrode?

Q.

The boiling points of three components A, B and C of a mixture are $80°\mathrm{C}$, $150°\mathrm{C}$ and $120°\mathrm{C}$, respectively. On fractional distillation, which of these components will be obtained at the top of the distillation column?

Q.

Name one each: The most abundant metal and non-metal in the earths crust.