Tag: chemistry

Questions Related to chemistry

The first electro-chemical was invented by:

electrical cells patterns and properties of metals chemistry

  1. Luigi Galvani.

  2. Alessandro Volta.

  3. Deniel.

  4. Lechanche

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Correct Option: A
Explanation:

The first electrochemical cell was invented by Luigi Galvani in 1791. It was greatly improved by Alessandro Volta in the years of 1800.

Statement $1$: In an electrolytic cell, the anode becomes positive and the cathode becomes negative.
Statement $2$: Anions migrate to the anode and cations migrate to the cathode.

electrical cells patterns and properties of metals chemistry

  1. Statement $1$ and Statement $2$ are correct and Statement 2 is the correct explanation of Statement $1$.

  2. Both the Statement $1$ and Statement $2$ are correct, but Statement $2$ is NOT the correct explanation of Statement $1$.

  3. Statement $1$ is correct, but Statement $2$ is not correct.

  4. Statement $1$ is not correct, but Statement $2$ is correct.

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Correct Option: B
Explanation:
|  In electrolytic cell |  In galvanic cell | | --- | --- | |  Anode $=+ve$ |  Anode $=-ve$ | |  Cathode $=-ve$ |  Cathode $=+ve$ |
Anions migrate to anode in electrolytic cell 
Cations migrate to cathode in electrolytic cell 

The apparatus in which electrical energy is converted into chemical energy is known as:

electrical cells patterns and properties of metals chemistry

  1. voltameter

  2. coulometer

  3. both (A) and (B)

  4. none of these

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Correct Option: C
Explanation:

The apparatus in which electrical energy is converted into chemical energy is known as voltameter or coulometer.
Ag or Cu voltameters or coulemeters are used to measure the total charge passed through solution in terms of mass of Ag or Cu deposited there on voltameter or coulometer cathode.

Consider a spontaneous electrochemical cell containing $Cd, Cd^{2+}, Ag^{+}$, and $Ag$.
The reduction potential of $Cd$ is $-0.403\ V$ and $Ag$ is $0.799\ V$.

What is the balanced equation for the reaction that is occurring, and what is the electrochemical cell voltage?

electrical cells patterns and properties of metals chemistry

  1. $Ag^{+} + Cd \rightarrow Cd^{2+} + Ag; 1.19\ V$

  2. $2Ag^{+} + Cd \rightarrow Cd^{2+} + 2Ag; 1.20\ V$

  3. $Ag^{+} + Cd \rightarrow Cd^{2+} + Ag^{+}; 0.40\ V$

  4. $2Ag^{+} + Cd \rightarrow Cd^{2+} + 2Ag; 2,30\ V$

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Correct Option: B
Explanation:
We have,
$E^0$ of Cd = -0.403V ( oxidation will favour)
$E^0$ of  Ag = 0.799V (reduction will favour)

So, the net reaction becomes:

$2 Ag^+ + Cd \rightarrow Cd^{2+} + 2Ag$

and $E^0 _{cell}  = 0.799 - (-0.403) = 1.202 V$

Which of the following is true of an electrolytic cell?

electrical cells patterns and properties of metals chemistry

  1. An electric current causes an otherwise non-spontaneous chemical reaction to occur.

  2. Reduction occurs at the anode

  3. A spontaneous electrochemical reaction produces an electric current

  4. The electrode to which the electrons flow is where oxidation occurs

  5. None of the above

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Correct Option: A
Explanation:

An electrolytic cell is a device which makes a non spontaneous reaction spontaneous by the use of electricity.

The chemical change in an electrolytic cell is non-spontaneous. 

electrical cells patterns and properties of metals chemistry

  1. True

  2. False

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Correct Option: A
Explanation:
An electrolytic cell converts electrical energy into chemical energy.
The redox reaction is not spontaneous and electrical energy has to be supplied to initiate the reaction. Both the electrodes are placed in a same container in the solution of molten electrolyte. Here, the anode is positive and cathode is the negative electrode. The reaction at the anode is oxidation and that at the cathode is reduction. The external battery supplies the electrons. They enter through the cathode and come out through the anode.

What is a voltaic cell?

electrical cells patterns and properties of metals chemistry

  1. A cell in which a spontaneous redox reaction produces electricity.

  2. A cell in which an oxidation reaction produces electricity.

  3. A cell that produces voltage.

  4. A cell full of volts.

  5. Any cell that undergoes a spontaneous reaction.

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Correct Option: A
Explanation:

A voltaic cell is a cell in which a spontaneous redox reaction produces electricity. It is an electrochemical cell and is also called galvanic cell. Chemical energy is converted into electrical energy. The dry cell, nickel cadmium cell, lead storage cell and fuel cells are examples of voltaic cell.

The value of equilibrium constant for a feasible cell reaction is:

electrical cells patterns and properties of metals chemistry

  1. $< 1$

  2. $= 1$

  3. $> 1$

  4. zero

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Correct Option: C
Explanation:

$K = antilog \left (\dfrac {nE^{\circ}}{0.0591}\right )$
For feasible cell, $E^{\circ}$ is positive, hence from the above equation $K > 1$ for feasible cell reactions.

An electrochemical cell consists of?

electrical cells patterns and properties of metals chemistry

  1. A cathode, anode, electrolyte, wire and two compartments.

  2. Cathode, anode, and wire

  3. Two compartments that conduct electricity.

  4. A positive and negative side.

  5. A cathode and an anode.

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Correct Option: E
Explanation:

An electrochemical cell consists of a cathode, anode, electrolyte, wire and two compartments. An electrochemical cell is a device used to study chemical reactions electrically.

Consider the reaction;
$Cl _2(g)+2Br^-(aq)\rightarrow 2Cl^-(aq)+Br _2$
The emf of the cell when
$[Cl^-]=[Br _2]=[Br]=0.01 M$ and $Cl _2$ gas at 1 atm pressure will be: ($E^0$ for the above reaction is = 0.29 volt)

electrical cells patterns and properties of metals chemistry

  1. 0.54 volt

  2. 0.35 volt

  3. 0.24 volt

  4. -0.29 volt

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Correct Option: A