H in H gas Pt electrode (SHE) Figure . Standard Hydrogen electrode XII U9 Electro XII U9 Electro - - - - Standard hydrogen electrode (cathode) H ( g ) ( atm) H + ( M) H 2H + ( aq ) + 2e - H ( g ) Digital voltmeter . Salt bridge Na SO (aq) (Na + ) 2e - Zn ZnSO (aq) SO - Zinc (anode) SO - Zn + e - e - e – ⇒ ⇒ .76V = (E + 0V (E V ox Zn Zn ox Zn Zn o + o + . This oxidation potential corresponds to the below mentioned half cell reaction which takes place at the cathode.
Zn Zn + 2e + (Oxidation) The emf for the reverse reaction will give the reduction potential Zn +2e Zn ; E = - .76V + o ∴ (E - .76V. red Zn Zn + IUPAC definition Electrode potential (E) Electromotive force of a cell in which the electrode on the left is a standard hydrogen electrode and the electrode on the right is the electrode in question. Standard electrode potential, E The value of the standard emf of a cell in which molecular hydrogen under standard pressure is oxidised to solvated protons at the left hand electrode. Evaluate yourself : .
The emf of the following cell at C is equal to .34v. Calculate the reduction potential of copper electrode. Pt (s) H (g, 1atm) H (aq, 1M) Cu aq, M) Cu (s) + ( . Using the calculated emf value of zinc and copper electrode, calculate the emf of the following cell at C .
Zn (s) Zn (aq, 1M) Cu (aq, 1M) Cu (s) + + Figure . emf measurement (Zn | Zn + electrode) XII U9 Electro XII U9 Electro - - - - Evaluate yourself : Write the overall redox reaction which takes place in the galvanic cell, Pt(s) Fe (aq),Fe (aq) MnO (aq), H (aq),Mn (aq) Pt(s) + + +