Tag: patterns and properties of metals

Questions Related to patterns and properties of metals

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

Show answer
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.

Show answer
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

In an electrochemical cell, anode and cathode are__________.

electrical cells patterns and properties of metals chemistry

  1. Positively and negatively charges ions

  2. Positively and negatively charges electrodes

  3. Negatively and positively charged electrodes

  4. Negatively and positively charged ions

Show answer
Correct Option: B
Explanation:

In both kinds of electrochemical cells, the anode is the electrode at which the oxidation half-reaction occurs, and the cathode is the electrode at which the reduction half-reaction occurs. The anode is considered positive and the cathode is considered negative. 


Hence, the correct option is $\text{B}$

Electrochemical cells are also called:

electrical cells patterns and properties of metals chemistry

  1. electrolytic cells

  2. galvanic cells

  3. fuel cells

  4. voltaic cells

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Correct Option: A,B,D
Explanation:

Electrochemical cell which convert electrical energy into chemical energy is called as electrolytic cell. 
Electrochemical cell which converts chemical energy into electrical energy is called as Galvanic or Voltaic cell

Foe the electrochemical cell:
$Zn\left( s \right) |{ Zn }^{ 2+ }\left( aq \right) \parallel { Cl }^{ - }\left( aq \right) |{ Cl } _{ 2 }\left( g \right) |Pt\left( s \right) $
Given : ${ E } _{ { Zn }^{ 2+ }/Zn }^{ o }=-0.76\ Volt$
             ${ E } _{ { Cl }^{ - }/{ Cl } _{ 2 }\left( g \right)  }^{ o }=-1.36\ Volt$
From these data one can deduce that:

electrical cells patterns and properties of metals chemistry

  1. $Zn + Cl _{2} \rightleftharpoons Zn^{2+} + 2Cl^{-}$ is a non-spontaneous reaction at standard conditions.

  2. $Zn^{2+} + 2Cl^{-} \rightleftharpoons Cl _{2} + Zn$ is a spontaneous reaction at standard conditions with ${ E } _{ cell }^{ o } = 2.12\ volt.$

  3. $Zn + Cl _{2} \longrightarrow Zn^{2+} + 2 Cl^{-}$ is a spontaneous reaction at standard conditions with ${ E } _{ cell }^{ o } = 2.12\ volt.$

  4. $Zn + Cl _{2} \longrightarrow Zn^{2+} + 2 Cl^{-}$ is a spontaneous reaction at standard conditions with ${ E } _{ cell }^{ o } = 0.60\ volt.$

Show answer
Correct Option: C
Explanation:
$Cl=\to zn^{2+} +2e^- \to Zn$
$2Cl\to Cl _2^- +2e^-$
for sponlareous reaction $E^o$ cell $>$ zero
$\Delta G <$ zero
$Zn^{3+}+2Cl^{-}\to Cl _2+Zn$ 
$Zn \to Zn^{2+} +2e^-$
$Cl _2 \to 2e^- \to 2Cl^- $(cathode)
$Zn +Cl _2 \to Zn^{3+}+2Cl^- ....(1)$
$E^o _{RP}$ (cathode) $=0.76$
$E^o $ cell $=E^o _{OP}+E^o _{RP}$
$=2.12$
as $E^o > 0$
$\Delta G < $ zero
so reaction $(1)$ is sponlareous at $2.12$

In an electrolytic cell:

electrical cells patterns and properties of metals chemistry

  1. anode is positively charged

  2. cathode is negatively charged

  3. oxidation takes place at anode

  4. reduction takes place at cathode

Show answer
Correct Option: A,B,C,D
Explanation:

In electrolytic cell,

anode is positively charged and $-ve$ charged ions are attracted to it and oxidation takes place by loss of electron,
cathode is negatively charged and $+ve$ charge ions are attracted to it and reduction takes place by gain of electron;
hence, all options are corrrect.