Electrochemistry

cathode (reduction)
anode (oxidation)

The of the cell reaction is calculated from
Nernst equation




is for

The given electrode process is:

Cl^-(aq) -> 1/2 Cl2(g) + e^-

The standard electrode potential for this process can be obtained from the reduction potential of chlorine gas and the standard reduction potential of the Cl^-/Cl^2- couple:

E°(Cl2/Cl^-) = 1.36 V (from standard reduction potential tables)

E°(Cl^-/Cl2-) = -E°(Cl2/Cl^-) = -1.36 V

The given EMF of the cell, Ecell, is -1.140 V, which is less negative than the standard reduction potential of the Cl^-/Cl2- couple. This means that the reaction is not at standard conditions and the reaction quotient Q is less than the equilibrium constant K.

The relationship between Ecell, E° and the reaction quotient Q is given by the Nernst equation:

Ecell = E° - (RT/nF) * ln Q

where R is the gas constant, T is the temperature in Kelvin, n is the number of electrons transferred in the reaction, F is the Faraday constant, and ln is the natural logarithm.

Substituting the values given in the problem, we get:

-1.140 V = -0.55 V - (0.0257 V/K) * ln Q

Solving for ln Q, we get:

ln Q = -22.48

Taking the exponential of both sides, we get:

Q = e^(-22.48) = 4.19 x 10^(-10)

The equilibrium constant K is related to the reaction quotient Q by the equation:

K = Q/[Cl^-]

where [Cl^-] is the concentration of chloride ions in the solution. Since the problem states that MCl is a sparingly soluble salt, we can assume that its concentration is much less than the concentration of chloride ions in the solution. Therefore, we can approximate [Cl^-] to be the same as the initial concentration of Cl^- in the solution, which is usually 1 M.

Thus, the equilibrium constant K is:

K = Q/[Cl^-] = (4.19 x 10^(-10))/1 = 4.19 x 10^(-10)

Therefore, the value of the equilibrium constant of the sparingly soluble salt MCl is in the order of 10^(-10).

Step 1: Understanding Refining Methods
- Vapour phase refining (Van Arkel method) is used for metals like Nickel (Ni).
- Zone refining is used for Silicon (Si) and other semiconductors.
- Liquation is used for Tin (Sn) to remove impurities with lower melting points.
- Electrolysis is commonly used for Copper (Cu) purification.

Step 2: Matching Correct Refining Methods
- (Nickel - Vapour phase refining)
- (Silicon - Zone refining)
- (Tin - Liquation)
- (Copper - Electrolysis)

Step 3: Conclusion
- The correct answer is Option (1): A - V, B - I, C - II, D - III.

The rate of disappearance of is ,
the formation of is ,
and the formation of is .
Balancing the coefficients, we find .

Step 1: The Nernst equation is used to calculate the electrode potential: where is the standard electrode potential (0.34 V for Cu), is the number of electrons transferred (2 for Cu), and is the concentration of .

Step 2: Substituting the values: Thus, the electrode potential is 0.281 V.