Variation of Specific, Equivalent and Molar Conductivities with Concentration

Q.

Explain Debye–Hückel Onsagar Law of the strong electrolyte.

Q. At ${25}^{\circ }C$ molar conductance of $0.1$ molar aqueous solution of ammonium hydroxide is $9.52$ ${\text{ohm}}^{-1}{\text{cm}}^2{\text{mol}}^{-1}$ and at infinite dilution its molar conductance is $238$ ${\text{ohm}}^{-1}{\text{cm}}^2{\text{mol}}^{-1}$. The percentage degree of dissociation of ammonium hydroxide at the same concentration and temperature is:
[1 Mark]

1. $4\%$
2. $40\%$
3. $20\%$
4. $2\%$

Q. At 291 K, the molar conductivities at infinite dilution of $N{H}_{4}Cl,NaOH$ and $NaCl$ are 129.8, 217.4 and $108.9Sc{m}^{2}mo{l}^{-1}$ respectively . If the molar conductivity of a centinormal solution of $N{H}_{4}OH$ is $9.532Sc{m}^{2}mo{l}^{-1}$, then calculate the dissociation constant of $N{H}_{4}OH$?

1. $1.6\times {10}^{-5}$
2. $5.2\times {10}^{-5}$
3. $1.6\times {10}^{-8}$
4. $9.6\times {10}^{-15}$

Q. Molar conductivity decreases with decrease in concentration

1. True
2. False

Q. (a) The conductivity of 0.001 $mol{L}^{-1}$ solution of $C{H}_{3}COOH$ is $3.905\times {10}^{-5}Sc{m}^{-1}$.
Calculate its molar conductivity and degree of dissociation $\alpha$.
Given ${\lambda }^{\circ }\left(H^{+}\right)=349.6Sc{m}^{2}mo{l}^{-1}$ and ${\lambda }^{\circ }\left(C{H}_{3}CO{O}^{-}\right)=40.9Sc{m}^{2}mo{l}^{-1}$.

(b) Define electrochemical cell. What happens if external potential applied becomes greater than $E_{cell}^{\circ }$ of electrochemical cell?

Q. Consider the statements S1 and S2 :
S1 : Conductivity always increases with decrease in the concentration of electrolyte.
S2 : Molar conductivity always increases with decrease in the concentration of electrolyte.
The correct option among the following is:

1. S1 is correct and S2 is wrong
2. S1 is wrong and S2 is correct
3. Both S1 and S2 are wrong
4. Both S1 and S2 are correct

Q.

Why is AC passed to the solution to measure conductivity?

Q.

A $\mathrm{KCl}$ solution of conductivity $0.14\mathrm{S}{\mathrm{m}}^{-1}$shows a resistance of $4.19\mathrm{ohm}$ in a conductivity cell. If the same cell is filled with an $\mathrm{HCl}$ solution, the resistance drops $1.03\Omega$. The conductivity of the $\mathrm{HCl}$ solution is $.............\times {10}^{-2}\mathrm{S}{\mathrm{m}}^{-1}$. (Round off to the Nearest Integer).

Q. is NO2 strong field ligand ?

Q. Depression in freezing point of 0.01 moll aqueous HCOOH solution is 0.02046. 1 molal aqueous urea solution freezes at - 1.86 ^°C, assuming molality equal to molarity, pH oh HCOOH solution is

Q. Consider the strong electrolytes $Z_m{X}_n,U_m{Y}_p\text{and}{V}_m{X}_n.$ Limiting molar conductivity $\left({\Lambda }^{\circ }\right)\text{of}{U}_m{Y}_p\text{and}{V}_m{X}_n$
are $250$ and $440Sc{m}^{2}mo{l}^{-1}$, respectively. The value of $(m+n+p)$ is ______.

Ion	$Z^{n+}$	$U^{p+}$	$V^{n+}$	$X^{m-}$	$Y^{m-}$
${\lambda }^{\circ }\left(sc{m}^{2}mo{l}^{-1}\right)$	$50.0$	$25.0$	$100.0$	$80.0$	$100.0$

${\lambda }^{\circ }$ s the limiting molar conductivity of ions
The plot of molar conductivity
$\left(\Lambda \right)\text{of}{Z}_m{X}_{n}vs{c}^{1/2}$ is given below.

Q.

If X is the specific resistance of the solution and M is the molarity of the

solution, the molar conductivity of the solution is given by

[Kurukshetra CEE 2002]

1. 
   

2. 
   

3. 
   

4. 
   

Q. Molar conductivity of a weak electrolyte AB at 0.01 M concentration was found to be 10 S cm2 mol–1. What will be the molar conductivity of this electrolyte when concentration is 0.005 M? The molar conductivity at infinite dilution is 400 S cm2 mol–1. Assume the degree of dissociation is negligible as compared to unity

Q. Conductivity of solution always decreases with decrease in concentration, both for weak and strong electrolytes.

1. True
2. False

Q. Conductivity of solution always decreases with decrease in concentration, both for weak and strong electrolytes.

1. True
2. False

Q. Which solution will show the highest resistance during the passage of current?

1. $0.05NNaCl$
2. $2NNaCl$
3. $0.1NNaCl$
4. $1NNaCl$

Q.

Among the following statements the one which is true for molar conductivity and conductivity is:

1. Limiting molar conductivity increases with dilution

2. Conductivity increases with dilution

3. When concentration approaches unity, molar conductivity is known as limiting molar conductivity

4. Both a and b are correct

Q. Why does the conductivity of a solution decreases with dilution?

Q. Calculate the solubility of a sparingly soluble salt, $BaS{O}_4$ in $0.02M$ $N{a}_{2}S{O}_4$ solution ?
$(K_{sp}$ for $BaS{O}_4=1.1\times {10}^{-10})$

1. $0.55\times {10}^{-8}mol{L}^{-1}$
2. $1.1\times {10}^{-9}mol{L}^{-1}$
3. $2.9\times {10}^{-5}mol{L}^{-1}$
4. $3.5\times {10}^{-7}mol{L}^{-1}$

Q.

The conductivity of 0.02 mol L^-1 KCl solution having the cell constant 1.29 cm^-1 and reisistance 520 Ω is:

1. 0.248 S m^-1

2. a. 0.248 S cm^-1

3. a. 24.8 S cm^-1

4. a. 2.48 S cm^-1

Q. The molar conductivity of 0.05 M BaCl_2 solution at 25^° C is 223 Ω^{-1}cm^2 mol^{-1}. What is its conductivity ?

Q. From the following molar conductivities at infinite dilution Calculate molar conductivity of aloh3 from al2so43 nh4oh nh42

Q. The dipole moment of ${NH}_3$ is ____ than that of ${NF}_3$.

1. less
2. more
3. equal
4. none

Q. When the solute-solute interaction of electrolytic solution increase,

1. the resistance will decrease
2. the resistance will remain constant
3. the conductance will increase
4. the conductance will decrease

Q. The physical constant which is less for $H_{2}O$ the $D_{2}O$ is

1. Dielectric constant
2. Ionic product
3. Solubility
4. Specific heat

Q.

Why does the addition of sulphuric acid to water produce a conducting solution?

Q.

Define conductivity and molar conductivity for the solution of an electrolyte. Discuss their variation with concentration.

Q. Which of the following(s) is/are true about an electrolyte solution at infinite dilution?

${\Lambda }_m$ is molar conductivity
${\Lambda }_m^0$ is limiting molar conductivity

1. $\text{Degree of dissociation of weak electrolyte,}\alpha =1$
2. Weak electrolyte is not fully dissociated
3. All interionic effects of electrolyte disappears
4. ${\Lambda }_m^0$ of an electrolyte is the sum of the individual contributions of cation and anion of the electrolyte.

Q. Conductivity of solution always decreases with decrease in concentration, both for weak and strong electrolytes.

1. True
2. False

Q. A $0.05M$ $N{H}_{4}OH$ solution offers the resistance of $50ohm$ to a conductivity cell at $298K$. If the cell constant is $0.50{cm}^{-1}$ and molar conductance of $N{H}_{4}OH$ at infinite dilution is $471.4{ohm}^{-1}{cm}^2{mol}^{-1}$, calculate :