Home
Class 12
CHEMISTRY
Explain why electrolysis of aqueous solu...

Explain why electrolysis of aqueous solution of NaCl gives `H_(2)` at cathode and `Cl_(2)` at anode. Write the overall reaction. [Given : `E_(Na^(+)//Na)^(@) = -2.71 V, E_(Cl_(2)//2Cl^(-))^(@) = 1.36 V`]
`1/2 O_(2)(g) + 2H^(+) (aq) + 2e^(-) to H_(2)O (l), E^(@) = 1.23 V`

Text Solution

Verified by Experts

The electrode reactions may be represented as under:
`NaCl(aq) to Na^(+) (aq) + Cl^(-) (aq)`
`H_(2)O(l) to H^(+) (aq) + OH^(-)` (aq)
At cathode: `2H^(+) (aq) + 2e^(-) to H_(2)` (g)
It is because reduction potential of `E_(H^(+)//H_(2))^(@)` is greater than that of `E_(Na^(+)//Na)^(@)`
At anode: `2Cl^(-)(aq) -2 e^(-) to Cl_(2) (g)`
It is because of overvoltage i.e., energy required to liberate `O_(2)` is more than that required to liberate `Cl_(2)`
Overall reaction: `2NaCl (aq) + 2H_(2)O (l) overset("Electrolysis") to H_(2)(g) + Cl_(2) (g) + 2Na^(+) (aq) + 2OH^(-)` (aq)
Promotional Banner

Topper's Solved these Questions

  • ELECTROCHEMISTRY

    U-LIKE SERIES|Exercise CASE BASED/SOURCE-BASED INTEGRATED QUESTIONS (LONG ANSWER QUESTIONS-I (3 MARKS EACH))|27 Videos

  • ELECTROCHEMISTRY

    U-LIKE SERIES|Exercise CASE BASED/SOURCE-BASED INTEGRATED QUESTIONS (LONG ANSWER QUESTIONS-II (5 MARKS EACH))|16 Videos

  • ELECTROCHEMISTRY

    U-LIKE SERIES|Exercise CASE BASED/SOURCE-BASED INTEGRATED QUESTIONS (VERY SHORT ANSWER QUESTIONS (1 MARK EACH))|47 Videos

  • COORDINATION COMPOUNDS

    U-LIKE SERIES|Exercise SELF ASSESSMENT TEST|7 Videos

  • EXAMINATION PAPER 2020

    U-LIKE SERIES|Exercise SECTION D|15 Videos

Similar Questions

Explore conceptually related problems

(a). Explain why electrolysis of an aqueous solution of NaCl gives H_(2) at cathode and Cl_(2) at anode. Given E_(Na^(+)//Na)^(@)=-2.71V,E_(H_(2)O//H_(2)^(@)=-0.83V E_(Cl_(2)//2Cl^(-))^(@)=+1.36V,E_(2H^(+)//(1)/(2)O_(2)//H_(2)O)^(@)=+1.23V (b). The resistance of a conductivity cell when filled with 0.05 M solution of an electrolyte X is 100Omega at 40^(@)C . the same conductivity cell filled with 0.01 M solution of electrolyte Y has a resistance of 50Omega . The conductivity of 0.05M solution of electrolyte X is 1.0xx10^(-4)scm^(-1) calculate (i). Cell constant (ii). conductivity of 0.01 M Y solution (iii). Molar conductivity of 0.01 M Y solution.

Assertion (A): The electrolysis of NaCl solution gives H_(2)(g) at cathode and Cl_(2)(g) at anode. Reason (R) : Cl_(2) has higher oxidation potential than H_(2)O

In what direction, can the reaction : 2NaCl+Fe_(2)(SO_(4))_(3) hArr 2FeSO_(4)+Cl_(2)+Na_(2)SO_(4) proceed spontaneously ? ("Given: "E_(Fe^(3+)//Fe^(2+))^(@)=0.77 V, E_(Cl^(-)//Cl^(2))^(@)=1.36 V)

If the half cell reactions are given as (i) Fe^(2+)(aq)+2e^(-)rarrFe(s),E^(@)=0.44V (ii) 2H^(+)(aq)+ 1//2O_(2)(g)+2e^(-)rarrH_(2)O(l),E^(@)=+1.23V The E^(@) for the reaction.

An aqueous solution containing Na^(+),Sn^(2+),Cl^(-) " & " SO_(4)^(2-) ions, all at unit concentration, is electrolysed between a silver anode and a platinum cathode. What changes occur at the electrodes when current is passed through the cell ? Given : E_(Ag^(+)|Ag)^(0)=0.799 V E_(Sn^(2+)|Sn)^(@)=-0.14V, E_(Cl_(2)|Cl^(-))^(@)=1.36 V, E_(S_(2)O_(8)^(2-)|SO_(4)^(2-))^(@)=2V, E_(Sn^(4+)|Sn^(2+))^(@)=0.13V

Use the standard reduction potentials to determine what is observed at the cathode during the electrolysis of a 1.0 M solution of KBr that contains phenolphthalein. O_(2)(g) + 4H^(+)(aq) + 4e^(-) rightarrow 2H_(2)O(l) E^(@) = 1.23V Br_(2)(l) + 2e^(-) rightarrow 2Br^(-)(aq) E^(@) = 1.07V 2H_(2)O(l) + 2e^(-) rightarrow H_(2)(g) + 2OH^(-) E^(@0 = -0.80V K^(+) (aq) + e^(-) rightarrow K(s) E^(@) = -2.92V

Calculate Delta G^(Theta) and the equilibrium constant for the cell reaction , Cl_2 + 2 I^(-) to 2 Cl^(-) + I_(2) Given that E_((Cl_(2) , Cl^(-)))^(Theta) = 1.36 V , E_((I_(2) , I^(-)))^(Theta) = 0.536V

U-LIKE SERIES-ELECTROCHEMISTRY -CASE BASED/SOURCE-BASED INTEGRATED QUESTIONS (SHORT ANSWER QUESTIONS (2 MARKS EACH))
  1. How long a current of 3 amperes has to be passed through a solution of...

    Text Solution

    |

  2. Consider the following diagram in which an electrochemical cell is cou...

    Text Solution

    |

  3. What advantages do the fuel cells have over primary and secondary batt...

    Text Solution

    |

  4. Write the Nernst equation for the cell reaction in the Daniel cell. Ho...

    Text Solution

    |

  5. Consider a cell given below: Cu | Cu^(2+) || Cl^(-) | Cl(2),Pt Wri...

    Text Solution

    |

  6. Write the cell reaction of a lead storage battery when it is discharge...

    Text Solution

    |

  7. Solutions of two electrolytes 'A' and 'B' are diluted. The Lambda(m) ...

    Text Solution

    |

  8. Blue colour of copper sulphate is slowly discharged when an iron rod i...

    Text Solution

    |

  9. Why on dilution the Lambda(m) of CH3COOH increases drastically, while...

    Text Solution

    |

  10. On the basis of the standard electrode potential values stated for aci...

    Text Solution

    |

  11. Estimate the minimum potential difference required to reduce Al(2)O(3)...

    Text Solution

    |

  12. The resistance of conductivity cell containing 0.001 M KCl solution at...

    Text Solution

    |

  13. Explain why electrolysis of aqueous solution of NaCl gives H(2) at ca...

    Text Solution

    |

  14. What are fuel cells ? Write the electrode reactions of a fuel cell whi...

    Text Solution

    |

  15. Zinc rod is dipped in 0.1 M solution of ZnSO4. The salt is 95% dissoci...

    Text Solution

    |

  16. Predict the products of electrolysis obtained at the electrodes in eac...

    Text Solution

    |

  17. Calculate the equilibrium constant for the following reaction at 298 K...

    Text Solution

    |

  18. What is corrosion ? Describe the role of zinc in cathodic protection o...

    Text Solution

    |

  19. The conductivity of 10^(-3) mol/L acetic acid at 25 °C is 4.1 xx 10^(-...

    Text Solution

    |

  20. Calculate the emf of the following cell at 298 K: Cr(s)//Cr^(3+) (0....

    Text Solution

    |