Electrochemistry - Physical Chemistry - Chemistry Previous Year Questions

The specific conductivity of a solution containing 1.0 g of anhydrous BaCl\(_2\) in 200 cm\(^3\) of the solution has been found to be 0.0058 Scm\(^{-1}\). The molar and equivalent conductivity of the solution respectively are

Given that molar conductances for Ba(OH)\(_2\), BaCl\(_2\) and NH\(_4\)Cl are 523.28, 280.0 and 129.8 \(\Omega^{-1}\) cm\(^2\) mol\(^{-1}\) respectively. What is the molar conductivity (\(\Omega^{-1}\) cm\(^2\) mol\(^{-1}\)) of NH\(_4\)OH?

Calculate the molar conductance of 0.025 M aqueous solution of calcium chloride at 25\(^\circ\)C. The specific conductance of calcium chloride is 12.04 \(\times\) 10\(^{-2}\) Sm\(^{-1}\)

What will be the emf of the following cell at 25\(^\circ\)C?

Fe/Fe\(^{2+}\) (0.001 M) | | H\(^+\) (0.01 M) | H\(_2\)(g) (1 Bar) | Pt(s)

\(E_{(F{e^{2+}} /Fe)}^o = - 0.44\) V; \(E_{({H^ + }/{H_2})}^o = - 0.00\) V

The Molar conductivity of \(0.05 \mathrm{M}\) solution of \(\mathrm{MgCl}_2\) is \(194.5 \mathrm{~ohm}^{-1} \mathrm{~cm}^2\) per mole at room temperature. A Conductivity cell with electrodes having \(3.0 \mathrm{~cm}^2\) surface area and \(1.0 \mathrm{~cm}\) apart is filled with the solution of \(\mathrm{MgCl}_2\). What would be the resistance offered by the conductivity cell?

If electrolysis of water is carried out for a time duration of 2 hours, how much electric current in amperes would be required to liberate \(100 \mathrm{~ml}\) of \(\mathrm{O}_2\) gas measured under standard conditions of temperature and pressure?

When Lead Storage battery is in the process of getting charged which one of the following reactions takes place?

The reaction taking place in a galvanic cell is as given

$$\mathrm{A}(\mathrm{s})+\mathrm{B}^{2+}\left(\mathbf{1} \mathbf{1} \mathbf{1 0} \mathbf{0}^{-\mathrm{M}} \mathbf{M}\right) \rightarrow \mathrm{B}_{(\mathrm{s})}+\mathrm{A}^{2+}(0.1 \mathrm{M}).$$

The emf of the cell is \(+2.651 \mathrm{~V}\). If the standard emf of the cell is \(+2.71 \mathrm{~V}\), what is the value of \(\mathrm{X}\) ?

Match the items in Column I with their description in Column II

The limiting molar conductivity of \(\mathrm{NH}_4 \mathrm{OH}\) is \(238 \mathrm{~S} \mathrm{~cm}^2 \mathrm{~mol}^{-1}\). At \(25^{\circ} \mathrm{C}\), molar conductance of \(0.1 \mathrm{M}\) aqueous solution of ammonium hydroxide is \(9.54 \mathrm{~S} \mathrm{~cm}^2 \mathrm{~mol}^{-1}\). The degree of ionisation of \(\mathrm{NH}_4 \mathrm{OH}\) at the same concentration and temperature is:

Identify the incorrect statement among the following.

The \(\mathrm{E}^{\circ}\) values of \(\mathrm{A} . \mathrm{B}\) and \(\mathrm{C}\) are given. Which element/(s) is/(are) good for coating the surface of iron to prevent corrosion? Given: \([\mathrm{E}_{\mathrm{Fe}^{2+} / \mathrm{Fe}}^0=-0.44 \mathrm{~V} ; \quad \mathrm{E}_{\mathrm{A}^{2+} / \mathrm{A}}^0=-2.37 \mathrm{~V} ; \quad \mathrm{E}_{\mathrm{B}^{2+} / \mathrm{B}}^0=-0.15 \mathrm{~V} ; \quad \mathrm{E}_{\mathrm{C}^{2+} / \mathrm{C}}^0=+0.34 \mathrm{~V}]\)

When 0.1 mole of \(\mathrm{MnO}_4{ }^{2-}\) is oxidised, the quantity of electricity required to completely oxidise \(\mathrm{MnO}_4{ }^{2-}\) to \(\mathrm{MnO}_4^{-}\) is

\(\mathrm{Cu}^{+}\) undergoes disproportionation, according to the equation,

$$2 \mathrm{Cu}^{+} \rightleftharpoons \mathrm{Cu}^{2+}+\mathrm{Cu}$$

The \(\mathrm{E}^{\circ}\) value for the reaction is:

$$[\mathrm{E}_{\mathrm{Cu}^{2+} / \mathrm{Cu}}^{\mathrm{o}}=0.34 \mathrm{~V} \text { and } \mathrm{E}_{\mathrm{Cu}^{2+} / \mathrm{Cu}^{+}}^{\mathrm{O}}=0.15 \mathrm{~V}]$$

What is the quantity of charge, in Faraday units, required for the reduction of 3.5 moles of \(\mathrm{Cr}_2 \mathrm{O} 7^{2-}\) in acid medium?

Arrange the following redox couples in the increasing order of their reducing strength:

$$\begin{array}{ll} \[{[\mathrm{A}]=\mathrm{Cu} / \mathrm{Cu}^{2+}} & \mathrm{E}^0=-0.34 \mathrm{~V} \\\] \[{[\mathrm{~B}]=\mathrm{Ag} / \mathrm{Ag}^{+}} & \mathrm{E}^0=-0.8 \mathrm{~V} \\\] \[{[\mathrm{C}]=\mathrm{Ca} / \mathrm{Ca}^{2+}} & \mathrm{E}^0=+2.87 \mathrm{~V} \\\] \[{[\mathrm{D}]=\mathrm{Cr} / \mathrm{Cr}^{3+}} & \mathrm{E}^0=+0.74 \mathrm{~V}\] \end{array}$$

Identify the correct statement regarding corrosion of iron rod left exposed to atmosphere.

A current of 3.0A is passed through 750 ml of 0.45 M solution of CuSO\(_4\) for 2 hours with a current efficiency of 90%. If the volume of the solution is assumed to remain constant, what would be the final molarity of CuSO\(_4\) solution?

Given below are 2 statements: Assertion and Reason. Choose the correct option.

Assertion: When Molar conductivity for a strong electrolyte is plotted versus \(\sqrt{C}(\mathrm{~mol} / \mathrm{L})^{1 / 2}\), a straight line is obtained with intercept equal to Molar conductivity at infinite dilution for the electrolyte and Slope equal to \(-\mathrm{A}\). All electrolytes of a given type have the same \(\mathrm{A}\) value.

Reason: At infinite dilution, strong electrolytes of the same type will have different number of ions due to incomplete dissociation.

A dry cell consists of a moist paste of \(\mathrm{NH}_4 \mathrm{Cl}\) and \(\mathrm{ZnCl}_2\) contained in a \(\mathrm{Zn}\) casing which encloses a Carbon rod surrounded by black \(\mathrm{MnO}_2\) paste. What is the role of \(\mathrm{ZnCl}_2\) in it?