Class 11th

8.30. Depict the galvanic cell in which the reaction, Zn(s) + 2Ag⁺(aq) → Zn²⁺(aq) + 2Ag(s)
takes place. Further show:
(i) Which of the electrode is negatively charged.
(ii) The carriers of current in the cell and
(iii) Individual reaction at each electrode. (Advance)

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The given redox reaction can be depicted as

Zn (s) + 2Ag⁺ (aq) → Zn²⁺ (aq) + 2Ag (s)
Since Zn gets oxidised to Zn²⁺ ions, and Ag⁺ gets reduced to Ag metal, therefore,

Oxidation occurs at the zinc electrode and reduction occurs at the silver electrode. Thus, galvanic cell corresponding to the above redox reaction may be depicted as:

Zn|Zn²⁺ (aq) | Ag⁺ (aq) | Ag

(i) Zinc electrode is negatively charged because oxidation occurs at the zinc electrode (i.e. electrons accumlulate on the zinc electrode)

(ii) The ions carry current. The electrons flow from Zn to Ag electrode while the current flows from Ag to Zn electrode.

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5.38. What is Boyle Temperature?

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5.38. The temperature at which a real gas obeys ideal gas law over an appreciable range of pressure, is called Boyle temperature or Boyle point.

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5.37. What is the effect of temperature on (i) surface tension and (ii) Viscosity?

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5.37. (i) Surface tension decreases with increase of temperature.

(ii) Viscosity decreases with increase of temperature.

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8.29. Given the standard electrode potentials,
K⁺/K = -2.93 V, Ag⁺/Ag = 0.80 V, Hg²⁺/Hg = 0.79 V, Mg²⁺/Mg = -2.37 V,
Cr³⁺/Cr = -0.74 V. Arrange these metals in increasing order of their reducing power.

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Lower the electrode potential, better is the reducing agent. Since the electrode potentials increase in the order: K⁺/K (-2.93 V), Mg²⁺/Mg (-2.37 V), Cr³⁺/Cr (-0.74 V), Hg²⁺/Hg (0.79 V), Ag⁺/Ag (0.80 V), therefore, reducing power of metals decreases in the same order, i.e., K, Mg, Cr, Hg, Ag.

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8.28. Arrange the following metals in the order in which they displace each other from the solution of their salts.

Al, Cu, Fe, Mg and Zn.

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Based on the relative positions of these metals in the activity series, the correct order is Mg, Al, Zn, Fe, Cu.

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5.36. Define Avogadro law, Dalton's law, Boyle's law and Charles' law.

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5.36. Avogadro law states that equal volumes of all gases under same conditions of temperature and pressure contain equal number of molecules.

Dalton's law of partial pressure states that total pressure exerted by a mixture of non-reacting gases is equal to the sum of partial pressures exerted by them.

Boyle's law states that under isothermal condition, pressure of a fixed amount of a gas is inversely proportional to its volume.

Charles' law is a relationship between volume and absolute temperature under isobaric condition. Itstates that volume of a fixed amount of gas is directly proportional to its absolute temperature (V? T)

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8.27. Predict the products of electrolysis in each of the following:
(i) An aqueous solution of AgNO₃ with silver electrodes.
(ii) An aqueous solution of silver nitrate with platinum electrodes.
(iii) A dilute solution of H₂SO₄with platinum electrodes.
(iv) An aqueous solution of CuCl₂with platinum electrodes.

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(i) An aqueous solution of AgNO₃? with silver electrodes.
At cathode: Silver ions have lower discharge potential than hydrogen ions. Hence, silver ions will be deposited in preference to hydrogen ions.

At anode: Silver anode will dissolve to form silver ions in the solution.
Ag → Ag⁺ + e⁻

(ii) An aqueous solution of AgNO_3? with platinum electrodes.

At cathode: Silver ions have lower discharge potential than hydrogen ions. Hence, silver ions will be deposited in preference to hydrogen ions.

At anode: Hydroxide ions having lower discharge potential will be discharged in preference to nitrate ions. Hydroxide ions wil

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8.26. Using the standard electrode potentials given in Table 8.1, predict if the reaction between the following is feasible:
(a) Fe³⁺(aq) and I^-(aq) (b) Ag⁺(aq) and Cu(s)
(c) Fe³⁺(aq) and Cu(s) (d) Ag(s) and Fe³⁺(aq)
(e) Br₂(aq) and Fe³⁺(aq). (Advance)

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(i) When emf is positive, the reaction is feasible.
E^o_{? cell} = E^o_{? Fe}? −E^o_{? I2}? =0.77−0.54=0.23V
Reaction is feasible.

(ii) E^o_?cell? =E^o_{? Ag}? −E^o_{? Cu}? =0.80−0.34=0.46V
Reaction is feasible.

(iii) E^o_?cell? =E^o_{? Fe}? −E^o_{? Cu}? =0.77−0.34 =0.43 V
Reaction is feasible.

(iv) E^o_?cell? =E^o_{? Fe}? −E^o_{? Ag}? =0.77−0.80=−0.03 V
Reaction is not feasible.

(v) E^o_?cell? =E^o_{? Br2?}? −E_Fe? =1.09−0.77=0.32 V
Reaction is feasible.

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5.35. What is critical temperature?

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5.35. When density of liquid and vapours becomes the same; the clear boundary between liquid and vapours disappears. This temperature is called critical temperature.

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8.25. In Ostwald's process for the manufacture of nitric add, the first step involves the oxidation of ammonia gas by oxygen gas to give nitric oxide gas and steam. What is the maximum Weight of nitric oxide that can be obtained starting only with 10.0 g of ammonia and 20.0 g of oxygen?

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