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प्रश्न
\[\ce{Λ^0_m H2O}\] is equal to:
(i) \[\ce{Λ^0_m_{(HCl)} + \ce{Λ^0_m_{(NaOH)} - \ce{Λ^0_m_{(NaCl)}}}}\]
(ii) \[\ce{Λ^0_m_{(HNO_3)} + \ce{Λ^0_m_{(NaNO_3)} - \ce{Λ^0_m_{(NaOH)}}}}\]
(iii) \[\ce{Λ^0_{(HNO_3)} + \ce{Λ^0_m_{(NaOH)} - \ce{Λ^0_m_{(NaNO_3)}}}}\]
(iv) \[\ce{Λ^0_m_{(NH_4OH)} + \ce{Λ^0_m_{(HCl)} - \ce{Λ^0_m_{(NH_4Cl)}}}}\]
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उत्तर
(i) \[\ce{Λ^0_m_{(HCl)} + \ce{Λ^0_m_{(NaOH)} - \ce{Λ^0_m_{(NaCl)}}}}\]
(iv) \[\ce{Λ^0_m_{(NH_4OH)} + \ce{Λ^0_m_{(HCl)} - \ce{Λ^0_m_{(NH_4Cl)}}}}\]
Explanation:
\[\ce{Λ^0_m_{(H_2O)} = \ce{Λ^0_m_{(HCl)} + \ce{Λ^0_m_{(NaOH)} - \ce{Λ^0_m_{(NaCl)}}}}}\]
\[\ce{Λ^0_{m(H^+)} + \ce{Λ^0_{m(OH^-)} = \ce{Λ^0_{m(H^+)} + \ce{Λ^0_{m(Cl^-)} + \ce{Λ^0_{m(Na^+)} + \ce{Λ^0_{m(OH^-)} - \ce{Λ^0_{m(Na^+)} - \ce{Λ^0_{m(Cl^-)}}}}}}}}}\]
\[\ce{Λ^0_m_{(HNO_3)} + \ce{Λ^0_m_{(NaOH)} - \ce{Λ^0_m_{(NaNO_3)} = \ce{Λ^0_m_{(H_2O)}}}}}\]
\[\ce{Λ^0_{m(H^+)} + \ce{Λ^0_{m(NO_3^-)} + \ce{Λ^0_{m(Na^+)} - \ce{Λ^0_{m(OH^-)} + \ce{Λ^0_{m(Na^+)} + \ce{Λ^0_{m(NO_3^-)} = \ce{Λ^0_{m(H^+)} - \ce{Λ^0_{m(OH^-)}}}}}}}}}\]
\[\ce{Λ^0_m_{(NH_4OH)} + \ce{Λ^0_m_{(HCl)} - \ce{Λ^0_m_{(NH_4Cl)} = \ce{Λ^0_m_{(H_2O)}}}}}\]
However, the sum of molar conductivities of constituent ions gives the molar conductivity of water but here \[\ce{NH4OH}\] is a weak electrolyte of which complete decomposition is not possible.
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संबंधित प्रश्न
The conductivity of 0.20 mol L−1 solution of KCl is 2.48 × 10−2 S cm−1. Calculate its molar conductivity and degree of dissociation (α). Given λ0 (K+) = 73.5 S cm2 mol−1 and λ0 (C1−) = 76.5 S cm2 mol−1.
Calculate the degree of dissociation (α) of acetic acid if its molar conductivity (Λm) is 39.05 S cm2 mol−1.
(Given \[\ce{\lambda^{\circ}_{(H^+)}}\] = 349.6 S cm2 mol−1 and \[\ce{\lambda^{\circ}_{(CH_3COO^-)}}\] = 40.95 S cm2 mol−1)
Define the following terms :
Limiting molar conductivity
How can you determine limiting molar conductivity, 0 m for strong electrolyte and weak electrolyte?
The S.I. unit of cell constant for conductivity cell is __________.
Molar conductivity denoted by the symbol Λm is related to the conductivity of the solution by the equation (k is the conductivity and c is the concentration).
Kohlrausch law of independent migration of ions states ____________.
Which of the statements about solutions of electrolytes is not correct?
Molar conductivity of ionic solution depends on:
(i) temperature.
(ii) distance between electrodes.
(iii) concentration of electrolytes in solution.
(iv) surface area of electrodes.
Assertion: Λm for weak electrolytes shows a sharp increase when the electrolytic solution is diluted.
Reason: For weak electrolytes degree of dissociation increases with dilution of solution.
Assertion: `"E"_("Ag"^+ //"Ag")` increases with increase in concentration of Ag+ ions.
Reason: `"E"_("Ag"^+ //"Ag")` has a positive value.
The limiting molar conductivities Λ° for NaCl, KBr and KCl are 126, 152 and 150 S cm2 mol–1 respectively. The limiting molar conductivity Λ° for NaBr is ______.
Which of the following halogen acids is the strongest reducing agent?
Which of the following increases with the increase in the concentration of the solution?
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.
The following questions are case-based questions. Read the passage carefully and answer the questions that follow:
| Rahul set up an experiment to find the resistance of aqueous KCl solution for different concentrations at 298 K using a conductivity cell connected to a Wheatstone bridge. He fed the Wheatstone bridge with a.c. power in the audio frequency range 550 to 5000 cycles per second. Once the resistance was calculated from the null point, he also calculated the conductivity K and molar conductivity ∧m and recorded his readings in tabular form. |
| S. No. | Conc. (M) |
k S cm−1 | ∧m S cm2 mol−1 |
| 1. | 1.00 | 111.3 × 10−3 | 111.3 |
| 2. | 0.10 | 12.9 × 10−3 | 129.0 |
| 3. | 0.01 | 1.41 × 10−3 | 141.0 |
Answer the following questions:
(a) Why does conductivity decrease with dilution? (1)
(b) If `∧_"m"^0` of KCl is 150.0 S cm2 mol−1, calculate the degree of dissociation of 0.01 M KCI. (1)
(c) If Rahul had used HCl instead of KCl then would you expect the ∧m values to be more or less than those per KCl for a given concentration? Justify. (2)
OR
(c) Amit a classmate of Rahul repeated the same experiment with CH3COOH solution instead of KCl solution. Give one point that would be similar and one that would be different in his observations as compared to Rahul. (2)
The solution of two electrolytes A and B are diluted. ^m of B increases 1.5 times while that of A increases 25 times. Which of the two is a strong electrolyte? Give a reason.
Discuss the variation of conductivity and molar conductivity with concentration.
