Advertisements
Advertisements
प्रश्न
Write cathode and anode reaction in a fuel cell.
उत्तर
Cell reactions in a fuel cell:
Oxidation at the anode (-):
Oxidation of hydrogen gas to water occurs at the anode.
2H2(g) + 4OH-(aq) →4H2O(l) + 4e-
Reduction at the cathode (+):
Reduction of oxygen gas to OH ions occurs at the cathode.
O2(g) + 2H2O(l) + 4e- → 4OH-(aq)
APPEARS IN
संबंधित प्रश्न
Derive a relation between ΔH and ΔU for a chemical reaction. Draw neat labelled diagram of calomel electrode. Resistance and conductivity of a cell containing 0.001 M KCI solution at 298K are 1500Ω and 1.46x10-4 S.cm-1 respectively.
Can you store copper sulphate solutions in a zinc pot?
Arrange the following metals in the order in which they displace each other from the solution of their salts.
\[\ce{Al, Cu, Fe, Mg}\] and \[\ce{Zn}\]
How many electrons flow through a metllic wire if a current of 0·5 A is passed for 2 hours? (Given : 1 F = 96,500 C mol−1)
Define the following term:
Fuel cell
How many faradays of electricity are required to produce 6 g of Mg from MgCl2?
E°cell for the given redox reaction is 2.71 V
Mg(s) + Cu2+ (0.01 M) → Mg2+ (0.001 M) + Cu(s)
Calculate Ecell for the reaction. Write the direction of flow of current when an external opposite potential applied is
(i) less than 2.71 V and
(ii) greater than 2.71 V
How many moles of electrons are required for reduction of 2 moles of Zn2+ to Zn?
For the electrochemical cell:
M | M+ || X− | X,
E0(M+ | M) = 0.44 V, E0(X | X−) = 0.33 V
Which of the following is TRUE for this data?
If 'I' stands for the distance between the electrodes and 'a' stands for the area of cross-section of the electrode, `"l"/"a"` refers to ____________.
A solution of CuSO4 is electrolysed using a current of 1.5 amperes for 10 minutes. What mass of Cu is deposited at cathode? [Atomic mass of Cu = 63.7]
What is the SI unit tor electrochemical equivalent?
A solution of Cu(NO3)2 is electrolyzed between platinum electrodes using 0.1 Faraday electricity. How many moles of Cu will be deposited at the cathode?
If one mole electrons is passed through the solutions of CrCl3, AgNO3 and NiSO4, in what ratio Cr, Ag and Ni will be deposited at the electrodes?
At 25°C, the emf of the following electrochemical cell.
\[\ce{Ag_{(s)} | Ag^+ (0.01 M) | | Zn^{2+} {(0.1 M)} | Zn_{(s)}}\] will be:
(Given \[\ce{E^0_{cell}}\] = −1.562 V)
Zinc can be coated on iron to produce galvanized iron but the reverse is not possible. It is because ____________.
In the electrochemical cell: Zn|ZnSO4 (0.01 M)||CuSO4 (1.0 M)|Cu, the emf of this Daniel cell is E1. When the concentration of ZnSO4 is changed to 1.0 M and that CuSO4 changed to 0.01 M, the emf changes to E2. From the above, which one is the relationship between E1 and E2?
A gas X at 1 atm is bubbled through a solution containing a mixture of 1MY− and 1MZ− at 25°C. If the reduction potential of Z > Y > X, then ____________.
Define cathode
Describe the electrolysis of molten NaCl using inert electrodes.
Why is anode in galvanic cell considered to be negative and cathode positive electrode?
Two metals M1 and M2 have reduction potential values of −xV and +yV respectively. Which will liberate H2 and H2SO4.
A copper electrode is dipped in 0.1 M copper sulphate solution at 25°C. Calculate the electrode potential of copper.
[Given: \[\ce{E^0_{{Cu^{2+}|Cu}}}\] = 0.34 V]
For the cell \[\ce{Mg_{(s)}|Mg^{2+}_{( aq)}||Ag^+_{( aq)}|Ag_{(s)}}\], calculate the equilibrium constant at 25°C and maximum work that can be obtained during operation of cell.
Given: \[\ce{E^0_{{Mg^{2+}|Mg}}}\] = −2.37 V and \[\ce{E^0_{{Ag^{+}|Ag}}}\] = 0.80 V
Electrode potential for Mg electrode varies according to the equation
`E_(Mg^(2+) | Mg) = E_(Mg^(2+) | Mg)^Θ - 0.059/2 log 1/([Mg^(2+)])`. The graph of `E_(Mg^(2+) | Mg)` vs `log [Mg^(2+)]` is ______.
Which of the following statement is not correct about an inert electrode in a cell?
Use the data given in below find out which option the order of reducing power is correct.
`"E"_("Cr"_2"O"_7^(2-)//"Cr"^(3+))^⊖`= 1.33 V `"E"_("Cl"_2//"Cl"^-)^⊖` = 1.36 V
`"E"_("MnO"_4^-//"Mn"^(2+))^⊖` = 1.51 V `"E"_("Cr"^(3+)//"Cr")^⊖` = - 0.74 V
Use the data given in below find out the most stable oxidised species.
`E^0 (Cr_2O_1^(2-))/(Cr_(3+))` = 1.33 V `E^0 (Cl_2)/(Cl^-)` = 1.36 V
`E^0 (MnO_4^-)/(MN^(2+))` = 1.51 V `E^0 (Cr^(3+))/(Cr)` = – 0.74 V
`E_(cell)^Θ` = 1.1V for Daniel cell. Which of the following expressions are correct description of state of equilibrium in this cell?
(i) 1.1 = `K_c`
(ii) `(2.303RT)/(2F) logK_c` = 1.1
(iii) `log K_c = 2.2/0.059`
(iv) `log K_c` = 1.1
For the given cell, \[\ce{Mg | Mg^{2+} || Cu^{2+} | Cu}\]
(i) \[\ce{Mg}\] is cathode
(ii) \[\ce{Cu}\] is cathode
(iii) The cell reaction is \[\ce{Mg^+ Cu^{2+} -> Mg^{2+} + Cu}\]
(iv) \[\ce{Cu}\] is the oxidising agent
Can absolute electrode potential of an electrode be measured?
Consider the following diagram in which an electrochemical cell is coupled to an electrolytic cell. What will be the polarity of electrodes ‘A’ and ‘B’ in the electrolytic cell?
How will the pH of brine (aq. \[\ce{NaCl}\] solution) be affected when it is electrolysed?
Assertion: Mercury cell does not give steady potential.
Reason: In the cell reaction, ions are not involved in solution.
The electrochemical cell stops working after some time because
Calculate the standard EMF ofa cell which involves the following cell reactions
\[\ce{Zn + 2 Ag+ -> Zn^{2+} + 2 Ag}\]
Given that \[\ce{E^{o}_{Zn/Zn^{2+}}}\] = 0.76 volt and \[\ce{E^{o}_{Ag/Ag^{+}}}\] = – 0.80 volt.
A current of 2.0 ampere passed for 5 hour through a molten salt deposits 22 g of the metal (Atomic mass = 177). The oxidation state of the metal in the metal salt is
If the half-cell reaction A + e– → A– has a large negative reduction potential, it follow that:-
The correct order of the mobility of the alkali metal ions. In aqueous solultion is
Read the passage given below and answer the questions that follow:
|
Oxidation-reduction reactions are commonly known as redox reactions. They involve transfer of electrons from one species to another. In a spontaneous reaction, energy is released which can be used to do useful work. The reaction is split into two half-reactions. Two different containers are used and a wire is used to drive the electrons from one side to the other and a Voltaic/Galvanic cell is created. It is an electrochemical cell that uses spontaneous redox reactions to generate electricity. A salt bridge also connects to the half-cells. The reading of the voltmeter gives the cell voltage or cell potential or electromotive force. If \[\ce{E^0_{cell}}\] is positive the reaction is spontaneous and if it is negative the reaction is non-spontaneous and is referred to as electrolytic cell. Electrolysis refers to the decomposition of a substance by an electric current. One mole of electric charge when passed through a cell will discharge half a mole of a divalent metal ion such as Cu2+. This was first formulated by Faraday in the form of laws of electrolysis.
|
- Is silver plate the anode or cathode? (1)
- What will happen if the salt bridge is removed? (1)
- When does electrochemical cell behaves like an electrolytic cell? (1)
- (i) What will happen to the concentration of Zn2+ and Ag+ when Ecell = 0. (1)
(ii) Why does conductivity of a solution decreases with dilution? (1)
OR
The molar conductivity of a 1.5 M solution of an electrolyte is found to be 138.9 S cm2mol-1. Calculate the conductivity of this solution. (2)
On which electrode the oxidation reaction takes place?
In a solution of CuSO4, how much time will be required to precipitate 2 g copper by 0.5 ampere current?
Galvanic cell is a device in which ______.
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
Can we construct an electrochemical cell with two half-cells composed of ZnSO4 solution and zinc electrodes? Explain your answer.
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?
Why is anode in galvanic cell considered to be negative and cathode positive?
What are electrochemical reactions?
Explain the types of electrochemical cells.
State the term for the following:
Two metal plates or wires through which the current enters and leaves the electrolytic cell.
