Advertisements
Advertisements
प्रश्न
Describe the electrolysis of molten NaCl using inert electrodes.
Advertisements
उत्तर
1. The electrolytic cell consists of two iron electrodes dipped in molten sodium chloride and they are connected to an external DC power supply via a key.
2. The electrode which is attached to the negative end of the power supply is called the cathode and the one is which attached to the positive end is called the anode.
3. Once the key is closed, the external DC power supply drives the electrons to the cathode and at the same time pulls the electrons from the anode.
Cell reactions:
Na+ ions are attracted towards the cathode, where they combine with the electrons and are reduced to liquid sodium.
Cathode (reduction)
\[\ce{Na^+_{ (l)} + e^- -> Na_{(l)}}\]
E0 = – 2.71 V
Similarly, Cl– ions are attracted towards anode where they losses their electrons and oxidised to chlorine gas.
Anode (oxidation)
\[\ce{2Cl^-_{ (l)} -> Cl2_{(g)} + 2e^-}\]
E0 = – 1.36 V
The overall reaction is,
\[\ce{2Na^+_{ (l)} + 2Cl^-_{ (l)} -> 2Na_{(l)} + Cl2_{(g)}}\]
E0 = 4.07 V
Electrolysis of molten NaCl
The negative E0 value shows that the above reaction is a non spontaneous one. Hence, we have to supply a voltage greater than 4.07 V to cause the electrolysis of molten NaCl.
In an electrolytic cell, oxidation occurs at the anode and reduction occurs at the cathode as in a galvanic cell, but the sign of the electrodes is the reverse i.e., in the electrolytic cell cathode is −ve and the anode is +ve.
APPEARS IN
संबंधित प्रश्न
For the electrochemical cell:
\[\ce{M | M+ || X- | X}\];
\[\ce{E^{\circ}_{{M^{+}/{M}}}}\] = 0.44 V,
\[\ce{E^{\circ}_{X/X^-}}\] = 0.33 V
Which of the following is TRUE for this data?
If one mole electrons is passed through the solutions of CrCl3, AgNO3 and NiSO4, in what ratio Cr, Ag and Ni will be deposited at the electrodes?
Assertion: pure iron when heated in dry air is converted with a layer of rust.
Reason: Rust has the compositionFe3O4.
Describe the construction of Daniel cell. Write the cell reaction.
A copper electrode is dipped in 0.1 M copper sulphate solution at 25°C. Calculate the electrode potential of copper.
[Given: \[\ce{E^0_{{Cu^{2+}|Cu}}}\] = 0.34 V]
For the given cell, \[\ce{Mg | Mg^{2+} || Cu^{2+} | Cu}\]
(i) \[\ce{Mg}\] is cathode
(ii) \[\ce{Cu}\] is cathode
(iii) The cell reaction is \[\ce{Mg^+ Cu^{2+} -> Mg^{2+} + Cu}\]
(iv) \[\ce{Cu}\] is the oxidising agent
Consider the following diagram in which an electrochemical cell is coupled to an electrolytic cell. What will be the polarity of electrodes ‘A’ and ‘B’ in the electrolytic cell?
The correct order of the mobility of the alkali metal ions. In aqueous solultion is
Read the passage given below and answer the questions that follow:
|
Oxidation-reduction reactions are commonly known as redox reactions. They involve transfer of electrons from one species to another. In a spontaneous reaction, energy is released which can be used to do useful work. The reaction is split into two half-reactions. Two different containers are used and a wire is used to drive the electrons from one side to the other and a Voltaic/Galvanic cell is created. It is an electrochemical cell that uses spontaneous redox reactions to generate electricity. A salt bridge also connects to the half-cells. The reading of the voltmeter gives the cell voltage or cell potential or electromotive force. If \[\ce{E^0_{cell}}\] is positive the reaction is spontaneous and if it is negative the reaction is non-spontaneous and is referred to as electrolytic cell. Electrolysis refers to the decomposition of a substance by an electric current. One mole of electric charge when passed through a cell will discharge half a mole of a divalent metal ion such as Cu2+. This was first formulated by Faraday in the form of laws of electrolysis.
|
- Is silver plate the anode or cathode? (1)
- What will happen if the salt bridge is removed? (1)
- When does electrochemical cell behaves like an electrolytic cell? (1)
- (i) What will happen to the concentration of Zn2+ and Ag+ when Ecell = 0. (1)
(ii) Why does conductivity of a solution decreases with dilution? (1)
OR
The molar conductivity of a 1.5 M solution of an electrolyte is found to be 138.9 S cm2mol-1. Calculate the conductivity of this solution. (2)
What is an electrochemical cell? What does it consist of?
