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Write the reaction occurring at anode and cathode and the products of electrolysis of aq KCl.
Concept: Applications of Electrolysis > Electroplating >> Products of Electrolysis
What is the pH of HCl solution when the hydrogen gas electrode shows a potential of −0.59 V at standard temperature and pressure?
Concept: Nernst Equation - Introduction
Molar conductivity of substance “A” is 5.9 × 103 S/m and “B” is 1 × 10–16 S/m. Which of the two is most likely to be copper metal and why?
Concept: Conductance of Electrolytic Solutions >> Variation of Conductivity and Molar Conductivity with Concentration
What is the quantity of electricity in Coulombs required to produce 4.8 g of Mg from molten MgCl2? How much Ca will be produced if the same amount of electricity was passed through molten CaCl2? (Atomic mass of Mg = 24 u, atomic mass of Ca = 40 u).
Concept: Electrolytic Cells and Electrolysis - Introduction
What is the standard free energy change for the following reaction at room temperature? Is the reaction spontaneous?
\[\ce{Sn(s) + 2Cu^{2+}(aq) -> Sn^{2+}(aq) + 2Cu+(s)}\]
Concept: Galvanic Cells - Measurement of Electrode Potential
Assertion (A) : Conductivity decreases with decrease in concentration of electrolyte.
Reason (R) : Number of ions per unit volume that carry the current in a solution decreases on dilution.
Concept: Conductance of Electrolytic Solutions >> Variation of Conductivity and Molar Conductivity with Concentration
Which of the following relations is incorrect?
Concept: Conductance of Electrolytic Solutions - Introduction
Assertion (A): Molar conductivity decreases with increase in concentration.
Reason (R): When concentration approaches zero, the molar conductivity is known as limiting molar conductivity.
Concept: Conductance of Electrolytic Solutions >> Variation of Conductivity and Molar Conductivity with Concentration
A voltaic cell is made by connecting two half cells represented by half equations below:
\[\ce{Sn^{2+}_{ (aq)} + 2e^- -> Sn_{(s)}}\], E0 = − 0.14 V
\[\ce{Fe^{3+}_{ (aq)} + e^- -> Fe^{2+}_{ (aq)}}\], E0 = + 0.77 V
Which statement is correct about this voltaic cell?
Concept: Galvanic or Voltaic Cells - Introduction
The unit of molar conductivity is ______.
Concept: Conductance of Electrolytic Solutions >> Variation of Conductivity and Molar Conductivity with Concentration
Which of the following solutions will have the highest conductivity at 298 K?
Concept: Conductance of Electrolytic Solutions >> Variation of Conductivity and Molar Conductivity with Concentration
Calculate the λ0m for Cl- ion from the data given below:
∧0m MgCl2 = 258.6 Scm2 mol-1 and λ0m Mg2+ = 106 Scm2 mol-1
Concept: Electrochemical Cells
Read the passage carefully and answer the questions that follow.
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The lead-acid battery represents the oldest rechargeable battery technology. Lead acid batteries can be found in a wide variety of applications including small-scale power storage such as UPS systems, ignition power sources for automobiles, along with large, grid-scale power systems. The spongy lead act as the anode and lead dioxide as the cathode. Aqueous sulphuric acid is used as an electrolyte. The half-reactions during discharging of lead storage cells are: Anode: \[\ce{Pb(s) + SO^{2-}_4 (aq) -> PbSO4 (s) + 2e-}\] Cathode: \[\ce{PbO (s) + 4H+ (aq) + SO^{2-}_4 (aq) + 2e- -> PbSO(s) + 2 H2O}\] There is no safe way of disposal and these batteries end - up in landfills. Lead and sulphuric acid are extremely hazardous and pollute soil, water as well as air. Irrespective of the environmental challenges it poses, lead-acid batteries have remained an important source of energy. Designing green and sustainable battery systems as alternatives to conventional means remains relevant. Fuel cells are seen as the future source of energy. Hydrogen is considered a green fuel. Problem with fuel cells at present is the storage of hydrogen. Currently, ammonia and methanol are being used as a source of hydrogen for fuel cell. These are obtained industrially, so add to the environmental issues. If the problem of storage of hydrogen is overcome, is it still a “green fuel?” Despite being the most abundant element in the Universe, hydrogen does not exist on its own so needs to be extracted from the water using electrolysis or separated from carbon fossil fuels. Both of these processes require a significant amount of energy which is currently more than that gained from the hydrogen itself. In addition, this extraction typically requires the use of fossil fuels. More research is being conducted in this field to solve these problems. Despite the problem of no good means to extract Hydrogen, it is a uniquely abundant and renewable source of energy, perfect for our future zero-carbon needs. |
Answer the following questions:
- How many coulombs have been transferred from anode to cathode in order to consume one mole of sulphuric acid during the discharging of lead storage cell?
- How much work can be extracted by using lead storage cell if each cell delivers about 2.0 V of voltage? (1 F = 96500 C)
- Do you agree with the statement – “Hydrogen is a green fuel.” Give your comments for and against this statement and justify your views.
OR
Imagine you are a member of an agency funding scientific research. Which of the following projects will you fund and why?
- safe recycling of lead batteries
- extraction of hydrogen
Concept: Batteries >> Secondary Batteries
Assertion (A): During electrolysis of aqueous copper sulphate solution using copper electrodes hydrogen gas is released at the cathode.
Reason (R): The electrode potential of Cu2+/Cu is greater than that of H+/H2.
Select the most appropriate answer from the options given below:
Concept: Electrolytic Cells and Electrolysis - Introduction
Can we construct an electrochemical cell with two half-cells composed of ZnSO4 solution and zinc electrodes? Explain your answer.
Concept: Electrochemical Cells
The cell constant of a conductivity cell is 0.146 cm-1. What is the conductivity of 0.01 M solution of an electrolyte at 298 K, if the resistance of the cell is 1000 ohm?
Concept: Electrochemical Cells
How much electricity in terms of Faraday is required to produce 40.0 g of Al from molten Al2O3?
(Given: Molar mass of Aluminium is 27 g mol−1.)
Concept: Electrolytic Cells and Electrolysis - Introduction
In a first order reaction x → y, 40% of the given sample of compound remains unreacted in 45 minutes. Calculate rate constant of the reaction.
Concept: Factors Influencing Rate of a Reaction
Sucrose decomposes in acid solution to give glucose and fructose according to the first order rate law. The half life of the reaction is 3 hours. Calculate fraction of sucrose which will remain after 8 hours.
Concept: Half Life Period of a Reaction
A reaction is second order in A and first order in B.
(i) Write the differential rate equation.
(ii) How is the rate affected on increasing the concentration of A three times?
(iii) How is the rate affected when the concentrations of both A and B are doubled?
Concept: Factors Influencing Rate of a Reaction
