Plus Two Chemistry Chapter Wise Previous Questions Chapter 3 Electrochemistry is part of Kerala Plus Two Chemistry Chapter Wise Previous Year Questions and Answers. Here we have given Plus Two Chemistry Chapter Wise Questions and Answers Chapter 3 Electrochemistry.
Kerala Plus Two Chemistry Chapter Wise Previous Questions and Answers Chapter 3 Electrochemistry
Define minimum boiling azeotropes with an example. [March 2018]
The solutions which show a large positive deviation from Raoult’s law from minimum boiling azeotrope at a particular composition.
E.g., 95% ethanol solution by volume.
Write the anode and cathode reactions occur in the operation of a lead storage battery. Mention the electrolyte used in the battery. [March 2018]
The electrolyte used is 38% H2SO4.
a. What are primary batteries?
b. The cell potential of mercury cell is 1.35 V, and remain constant during its life. Give reason.
c. Write the equations of the reactions involved at each electrode in an H2O2 fuel cell. [March 2018]
a. Batteries which cannot be recharged or reused. Or, here the reaction occurs only once.
b. Since the overall reaction does not involve any ion in solution.
c. Anode reaction:
a. Represent the galvanic cell based on the cell reaction given below:
b. Write the half cell reactions of the above cell.
c. for NaCl, HCl and NaAc are 126.4, 425.9 and 91.0 S cm2 mol-1 respectively. Calculate for HAc.
i. Which of the following is a secondary cell?
a. Dry cell
b. Leclanche cell
c. Mercury cell
d. None of these
ii. What is the relationship between resistance and conductance?
iii. One of the fuel cells uses the reaction of hydrogen and oxygen to form water. Write down the cell reaction taking place in the anode and cathode of the fuel cell. [March 2016]
i. d. None of these
ii. Conductance (C) is the reciprocal of the resistance (R). C = 1/R
iii. The electrode reactions are:
The overall reaction is
You are supplied with the following substances: Copper rod, Zinc rod, Salt bridge, two glass beakers, a piece of wire, 1 M CuSO4 solution, 1 M ZnSO4 solution.
a. Represent the cell made using the above materials.
b. i. Write the Nernst equation for the above cell.
ii. Calculate the standard EMF of the cell if
a. This is a Daniel cell. Copper act as cathode and Zian as an anode.
i. Primary cells cannot be recharged and used again. The electrode reactions are not reversible. Secondary cells can be recharged and reused. The electrode reactions are reversible on the passage of electricity.
a. The cell reaction in Daniel cell is
and Nernst equation for a single electrode potential for general electrode reaction
Derive Nernst equation for Daniel cell. [March 2014]
b. Daniel cell is a primary cell while lead storage cell is a secondary cell. Write any one difference between primary cells and secondary cells.
a. The overall cell reaction in a Daniel cell is,
b. a. Primary cells cannot be recharged and used again. The electrode reactions are not reversible. Secondary cells can be recharged and reused. The electrode reactions are reversible on the passage of electricity.
The galvanic cell is a device which converts chemical energy to electrical energy.
a. Give the diagrammatic representation of the cell Mg / MgSO4 II CuSO4/ Cu. Write the half-cell reactions take place in this cell.
b. Explain the mechanism of corrosion using electrochemical theory.
c. How many coulombs of electricity are required for the reduction of 1 mol of MnO4 to Mn2+? [March2014]
b. The spot where oxidation take place behaves as anode. The reaction take place at anode is 2Fe + 2Fe2+ + 4; E0 = -0.44V
The electrons released at the anodic spot move through the metal and reduce oxygen at another spot in the presence of H+ ion. This spot behaves as cathode. The reaction taking place at cathode is given by O2 + 4H+ + 4e– → 2H2O The overall reaction is 2Fe + O2+ 4H+ → 2Fe2+ + 2H2O
The Fe2+ ions thus formed are further oxidised by atmospheric oxygen to Fe3+ ions, and finally, it comes out as rust.
c. Charge required 1 mole of MnO4 to Mn2+ is 5 F = 5 × 96500 C = 4.825 × 105 C ,
With a decrease in concentration of an electrolytic solution, conductivity (K) decreases and molar conductivity (Δm) increases.
i. Write the equation showing the relationship between conductivity and molar conductivity.
ii. How will you account for the increase in molar conductivity with a decrease in concentration?
iii. Limiting molar conductivity (Δ°m ) of a strong electrolyte can be determined by graphical extrapolation method. Suggest a method for the determination of limiting molar conductivity of a weak electrolyte, taking acetic acid (CH3COOH) as an example. [March 2013]
i. Molar conductivity, ; where K is the conductivity of the solution and C is the concentration of the solution.
ii. The molar conductivity increases with. a decrease in concentration for both strong and weak electrolytes.
In weak electrolytes, this is due to the increase in the degree of dissociation which increases the total number of ions. In strong electroytes λm increases on dilution because of decrease in the interionic hindrance towards the mobility of the ions.
iii. Limiting molar conductivity of acetic acid is obtained by using Kohlrausch’s law of independent migration of ions. It is possible to calculate for acetic acid from of individual ions.
Daniel cell is a galvanic cell made of zinc and copper electrodes.
i. Write anode and cathodb reactions in Daniel cell.
ii. Nernst equation for the electrode reaction,
Derive Nernst equation for Daniel cell. [March2012]
i. This is a Daniel cell. Copper act as cathode and Zian as an anode.
ii. The overall cell reaction in a Daniel cell is,
a. Write any two differences between primary cells and secondary cells?
b. What is a fuel cell?
c. Write the overall cell reaction in H2O2 fuel cell? [March2011 ]
a. Primary cells cannot be recharged and used again. The electrode reactions are not reversible. Secondary cells can be recharged and reused. The electrode reactions are reversible on the passage of electricity.
b. A galvanic cell that converts the energy of combustion of fuels like hydrogen or methane directly into electrical energy is called a fuel cell.
i. What is a galvanic cell?
ii. Name the anode and cathode of the Daniel cell.
iii. Write the name of the half-cell represented by Pt (s) I H2 (g) I H+ (aq)
iv. What is the potential of the above half-cell at all temperatures? [March2010]
i. A galvanic cell is an electrochemical cell that converts chemical energy into electrical energy.
ii. The anode is zinc and cathode is copper.
iii. Standard hydrogen electrode.
The limiting molar conductivity of an electrolyte is obtained by adding the limiting molar conductivities of cation and anion of the electrolyte.
a. Name the above law.
b. What is meant by limiting molar conductivity?
c. Explain how conductivity measurements help to determine the ionisation constant of a weak electrolyte like acetic acid?
d. Explain the change of conductivity and molar conductivity of a solution with dilution. [March2011, 2009]
a. Kohlrausch’s law.
b. It is the molar conductivity of electrolytes at zero concentration or at infinite dilution.
c. The degree of dissociation can be km determined by the equation, To obtain ionisation constant, Ka, substitute a in the following equation, ; where C is the concentration of acetic acid in moles/litre.
d. Conductivity of a solution decreases with the decrease in concentration as the number of ions presents per unit volume of the solution actually decreases. The molar conductivity of electrolytes increases with a decrease in concentration.
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