हिंदी
कर्नाटक बोर्ड पी.यू.सी.पीयूसी विज्ञान 2nd PUC Class 12

Suggest a way to determine the ∧_"m"^∘ alue of water. - Chemistry

Advertisements
Advertisements

प्रश्न

Suggest a way to determine the `∧_"m"^∘`value of water.

संख्यात्मक
Advertisements

उत्तर

Water is a weak electrolyte. Its `∧_"m"^∘`value can be determined with the help of Kohlrausch's law.

`∧_"m"^∘("HCl") = ∧_"m"^∘("H"^+) + ∧_"m"^∘("Cl"^-)`   ...(i)

`∧_"m"^∘("NaOH") = ∧_"m"^∘("Na"^+) + ∧_"m"^∘("OH"^-)`   ...(ii)

`∧_"m"^∘("NaCl") = ∧_"m"^∘("Na"^+) + ∧_"m"^∘("Cl"^-)`   ...(iii)

By adding (i) and (ii) and subtracting (iii) we get

`∧_"m"^∘("H"_2"O") = ∧_"m"^∘("H"^+) + ∧_"m"^∘("OH"^-)`

= `∧_"m"^∘("HCl") + ∧_"m"^∘("NaOH") - ∧_"m"^∘("NaCl")`

shaalaa.com
  क्या इस प्रश्न या उत्तर में कोई त्रुटि है?
अध्याय 2: Electrochemistry - Intext Questions [पृष्ठ ५१]

APPEARS IN

एनसीईआरटी Chemistry Part 1 and 2 [English] Class 12
अध्याय 2 Electrochemistry
Intext Questions | Q 2.8 | पृष्ठ ५१

संबंधित प्रश्न

Define limiting molar conductivity.


Why conductivity of an electrolyte solution decreases with the decrease in concentration ?


Define the following terms: Molar conductivity (m)


Write mathematical expression of molar conductivity of the given solution at infinite dilution.


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)


 How can you determine limiting molar conductivity,   0 m for strong electrolyte and weak electrolyte?


A steady current of 2 amperes was passed through two electrolytic cells X and Y connected in series containing electrolytes FeSO4and ZnSO4 until 2.8g of Fe deposited at the cathode of cell X. How long did the current flow? Calculate the mass of Zn deposited at the cathode of cell Y. 
(Molar mass: Fe=56g mol-1,Zn=65.3g mol-1,1F=96500C mol-1)


In the plot of molar conductivity (∧m) vs square root of concentration (c1/2), following curves are obtained for two electrolytes A and B:

Answer the following:
(i) Predict the nature of electrolytes A and B.
(ii) What happens on extrapolation of ∧m to concentration approaching zero for electrolytes A and B?


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 ____________.


Why on dilution the m Λm of \[\ce{CH3COOH}\] increases very fast, while that of \[\ce{CH3COONa}\] increases gradually?


Solutions of two electrolytes ‘A’ and ‘B’ are diluted. The Λm of ‘B’ increases 1.5 times while that of A increases 25 times. Which of the two is a strong electrolyte? Justify your answer. Graphically show the behavior of ‘A’ and ‘B’.


An increase in equivalent conductance of a strong electrolyte with dilution is mainly due to :-


Which of the following increases with the increase in the concentration of the solution?


The molar conductance of NaCl, HCl and CH3COONa at infinite dilution are 126.45, 426.16 and 91.0 S cm2 mol−1 respectively. The molar conductance of CH3COOH at infinite dilution is ______.

Choose the right option for your answer.


Given below are two statements:

Statements I: The limiting molar conductivity of KCl (strong electrolyte) is higher compared to that of CH3COOH (weak electrolyte).

Statement II: Molar conductivity decreases with decrease in concentration of electrolyte.
In the light of the above statements, choose the most appropriate answer from the options given below:


Assertion (A): Molar conductivity decreases with increase in concentration.

Reason (R): When concentration approaches zero, the molar conductivity is known as limiting molar conductivity.


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 specific conductance of 2.5 × 10-4 M formic acid is 5.25 × 10-5 ohm-1 cm-1. Calculate its molar conductivity and degree of dissociation.

Given `λ°_("H"^+)` = 349.5 ohm-1 cm2 mol-1 and

`λ°_("HCOO"^-)  = 50.5 " ohm"^-1 "cm"^2  "mol"^-1`


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×