The Cell Ag ( s ) Ag 2 SO 4 ( s ) Hg 2 SO 4 ( aqstt ) Hg s SO 4 ( s ) Hg ( i ) ∣ P t ( s ) has emf of 0.140V at 298K and 1 bar. Close to 298 K emf varies with temperature by 1.39 × 10 – 4 V K – 1 . How much heat is absorbed by the cell if it discharges isothermally and reversibly to deposit one gram equivalent of copper from its aqueous solution in units of KJ? (1 F = 96479 C)
In the following process of disproportionation, 2 C l O 3 − C h l o r a t e i o n ⇌ C l O 2 − + C l O 4 − P e r c h l o r a t e i o n ; E C l O 4 − / C l O 3 − o = + 0.36 V E C l O 3 − / C l O 2 − o = + 0.33 V Initial concentration of chlorate ion was 0.1 M. The equilibrium concentration of per chlorate ion will be 1.9 × 10 − x . Hence x is
An amount of 20g potassium sulphate was dissolved in 150 cm3 of water. The solution was then electrolysed. After electrolysis the content of potassium sulphate in the solution was 15% by mass. Determine volume of the gases obtained at NTP ? ( d H2O = 1 g cm –3 )
The measured reduction potential for the reaction Zn 2+ + 2e – Zn (s) depends upon
If K c for the reaction Cu 2 + ( aq ) + Sn 2 + ( aq ) ⟶ Sn 4 + ( aq ) + Cu ( s ) at 25° C is represented as 2.6 × 10 y then find the value of y. (Given : E Cu 2 + ∣ Cu ∘ = 0 .34 V ; E Sn 4 + ∣ Sn 2 + ∘ = 0 .15 V )
If the e.m.f of a galvanic cell is negative, it implies that :
The cell potential (E cell ) of a reaction is related as ΔG = − nFE cell , where ΔG represents max. useful electrical work n = no. of moles of electrons exchanged during the reaction for reversible cell reaction d ( ΔG ) = Δ r V dp − Δ r S ⋅ dT at constant pressure d ( ΔG ) = − Δ r S ⋅ dT ∵ At constant pressure ΔG = ΔH − T ⋅ ΔS . . . . (1) ∴ ΔG = ΔH + T d ( ΔG ) dT p . . . . .(2) dE cell dT p is known as temperature coefficient of the e.m.f of the cell
The oxidation potential of hydrogen half-cell will be negative if
How many faradays are required for reduction of 1 mol C 6 H 5 NO 2 into C 6 H 5 NH 2 ?
Calculate the cell potential (in V) if ΔG = − 96 .5 kJ / mol and n = 1 .
During discharge of a lead storage cell the density of sulphuric acid in the cell
The standard electrode potential for the following reaction is +1.33 V. The potential at pH = 2.0 cannot be Cr 2 O 7 2- aq,1M + 14 H + aq + 6e – 2Cr 3+ aq, 1M + 7H 2 O l
0.2 F of electricity is passed through 20 lit of a solution of aqueous solution of NaCl. p H of the solution after electrolysis is ——————
Match the electrode with its composition
E A + / A 0 = 0 . 5 V ; E B + / B 0 = 0 . 2 V ; E C + / C 0 = – 0 . 3 V ; E D + / D 0 = – 0 . 1 V Based on above data select correct statements under standard condition
Indicate the correct statements:
An electrolytic cell is set up to obtain pure copper from an impure rod of copper. The electrolyte solution contains both copper (II) sulfate and sulfuric acid. Impure rod of the copper, Electrode I, contains impurities such as zinc (22%), cobalt (5.8%), silver(2%), gold(1.2%), nickel(1.8%) and iron(12.3%) and inert materials which are non oxidizable. The cell voltage is adjusted so that only copper is deposited on Electrode II. Sludge, which contains some of the solid metal impurities present in the copper rod, forms beneath Electrode I. The other impurities remain in solution as ions. The diagram below represents the cell. Which one of the following graphs shows the change in mass of Electrode-I over a period of time, starting from the moment the power supply is connected?
Conductometric titration is a type of titration in which electrolytic conductivity of reaction mixture is continuously monitored as one reactant is added. The equivalence point is the point at which the conductivity undergoes a sudden change.
Consider a 70% efficient hydrogen-oxygen fuel cell working under standard conditions at 1 bar and 298 K. Its cell reaction is H 2 ( g ) + 1 2 O 2 ( g ) H 2 O ( ℓ ) The work derived from the cell on the consumption of 1.0 × 10 –3 mol of H 2 (g) is used to compress 1.00 mol of a monoatomic ideal gas in a thermally insulted container. What is the change in the temperature (in K) of the ideal gas ? The standard reduction potentials for the two half-cells are given below. O 2 ( g ) + 4 H + ( aq . ) + 4 e − 2 H 2 O ( ℓ ) , E o = 1.23 V 2 H + ( aq . ) + 2 e − H 2 ( g ) , E o = 0.00 V Use F = 96500 C mol –1 , R = 8.314 J mol –1 K –1
For reversible operation of the lead storage cell (given in following figure) at 298 K and all species in the cell in their standard state, Select the correct statement(s) based on following data. Half cell reaction E°(volt) PbO 2 ( s ) + SO 4 − 2 ( aq ) + 4 H + ( aq ) 2 e − PbSO 4 ( s ) + 2 H 2 O ( ℓ ) + 1.7 V PbO 2 ( s ) + 4 H + + 2 e − Pb + 2 ( aq ) + 2 H 2 O ( ℓ ) + 1.46 V Pb + 2 ( aq ) + 2 e − Pb ( s ) − 0.13 V PbSO 4 ( s ) + 2 e − Pb ( s ) + SO 4 − 2 ( aq ) ΔH ∘ of the overall cell reaction = − 306 kJ / mol
A 60 ml sample solution of KI was electrolysed for 579 sec using a 5 amp constant current. The produced, completely reacted with 0.20 M sodium thiosulphate solution and unreacted KI solution required 30 ml of 0.04 M acidic solution of KMnO 4 . If the original molarity of KI solution can be expressed in scientific notation as Y × 10 -1 . Calculate the value of Y.
The conductivity of a saturated solution of Ag 2 C 2 O 4 is 4 × 10 − 5 S c m − 1 at 25°C. Conductivity of water is 6 × 10 − 8 S c m − 1 . What is the approximate molar conductivity of C 2 O 4 2 − ion at infinite dilution, given molar conductivity of Ag+ ions at infinite dilution is 62 S c m 2 / m o l and K sp Ag 2 C 2 O 4 = 3 .2 × 10 − 11
Match the column Column I Column II (P) Na + ( a q ) + e − ⟶ Na ( s ) (1) Reaction taking place at anode during electrolysis of very dilute solution of NaCl using Pt electrodes. (Q) The concentration of CuSO 4 solution does not change on electrolysis (2) Reaction taking place at anode during electrolysis of CuSO 4 using Cu electrode. (R) Cu ( s ) ⟶ Cu 2 + ( aq ) + 2 e – (3) Electrolysis of aqs CuSO 4 using Cu electrodes (S) 4 OH − ⟶ 2 H 2 O + O 2 + 4 e – (4) Reaction taking place at cathode when electrolysis of aq NaCl is done using Hg electrode
Cu 2 + + 2 e ⟶ Cu ; log Cu 2 + vs . E red graph is of the type as shown in figure where OA = 0.34V, then electrode potential of the half-cell of Cu ;Cu 2+ (0.1 M) will be:
Which of the following expressions represent the EMF of the above cell at 25°C?
The reduction potential of hydrogen half-cell will be negative if:
EMF of cell Ni Ni 2 + ( 1 .0 M ) ∥ Au 3 + ( 1 .0 M ) Au is……., if E ∘ for Ni 2 + ∣ Ni is − 0 .25 V , E ∘ for Au 3 + ∣ Au is 1 .50 V .
The reduction electrode potential E, of 0.1M solution of M + ions ( E RP ° = – 2.36 V) is:
The standard EMF for the cell reaction, Zn + Cu 2 + ⇔ Cu + Zn 2 + is 1.10 volt at 25 ∘ C . The EMF for the cell reaction, when 0.1 Cu 2 + and 0 .1 M Zn 2 + solutions are used, at 25°C is:
For the cell prepared from electrode A and B; Electrode A : Cr 2 O 7 2 − ∣ Cr 3 + , E red ∘ = + 1.33 V and Electrode B : Fe 3 + ∣ Fe 2 + , E red ∘ = 0 .77 V Which of the following statements is/are correct ?
If the cell reaction is spontaneous the
A current of 2.0 A passed for 5 hr. through a molten metal salt deposits 22.2 g of metal (at. mass 177). The valency of the metal in the metal salt is:
The term infinite dilution refers for:
Which ions has exceptionally higher λ ∞ values ?
An alloy of Pb-Ag weighing 1.08 g was dissolved in dilute HNO 3 and the volume made to 100 mL. A silver electrode was dipped in the solution and EMF of the cell set up was Pt ( s ) , H 2 ( g ) H + ( 1 M ) ∥ Ag ( a q . ) + Ag ( s ) 0.62 V. The percentage of Ag in the alloy is: E cell ∘ = 0 .80 V , 2 .303 RT / F = 0 .06 at 25 ∘ C
For a saturated solution of AgCl at 25°C, specific conductance 3.41 × 10 -6 ohm -1 cm -1 and of water used for preparing. The solution is 1.60 × 10 -6 ohm -1 cm -1 . If λ AgCl ∞ = 138.3 ohm -1 cm 2 eq -1 , the K sp of AgCl is 0.17 × 10 -x M 2 . The value of x is
Select correct statement(s) about electrolysis
If the half-cell reaction A + e − ⇔ A − has a large negative reduction potentials, incorrect observations with reference to electrode reaction is
When a molten salt was electrolysed for 5 min with 9.65 A current, 0.18 g of the metal was deposited. Calculate the Eq. mass of metal.
What is the equivalent mass of O 2 in the following reaction, H 2 O + 1 2 O 2 + 2 e − ⟶ 2 OH − ?
