Advertisements
Advertisements
प्रश्न
Calculate emf of the cell at 25°C.
Zn(s) | Zn2+ (0.08 M) || Cr3+ (0.1 M) | Cr(s)
`E_(Zn)^0` = −0.76 V, `E_(Cr)^0` = −0.74 V
Advertisements
उत्तर
Given: `E_(Zn)^0` = −0.76 V, `E_(Cr)^0` = −0.74 V
To find: Emf of the cell `(E_(cell))`
Formulae:
1) `E_(cell)^0 = E_(cathode)^0 - E_(anode)^0`
2) `E_(cell) = E_(cell)^0 - (0.0592 V)/n log_10 [["Product"]]/[["Reactant"]]`
Calculation:
\[\ce{[Zn_{(s)} -> Zn^{2+}_{(0.08 M)} + 2e-] × 3}\] (oxidation at anode)
\[\ce{[Cr^{3+}_{(0.1 M)} + 3e- -> Cr_{(s)}] × 2}\] (reduction at cathode)
___________________________________________________
\[\ce{3Zn_{(s)} + 2Cr^{3+}_{(0.1 M)} -> 3Zn^{2+}_{(0.08 M)} + Cr_{(s)}}\] (overall reaction)
Using formula (1),
`E_(cell)^0 = E_(cathode)^0 - E_(anode)^0`
`E_(cell) = E_(Cr)^0 - E_(Zn)^0`
= −0.74 V − (−0.76 V)
= 0.02 V
Using formula (2),
The cell potential is given by
`E_(cell) = E_(cell)^0 - (0.0592 V)/n log_10 [["Product"]]/[["Reactant"]]`
= `0.02 - (0.0592 V)/6 log_10 (0.08)^3/(0.1)^2`
= `0.02 - 9.867 × 10^-3 log_10 (5.12 × 10^-4)/(1 × 10^-2)`
= `0.02 - 9.867 × 10^-3 × bar 2. 7093`
= 0.02 − 9.867 × 10−3 × (−1.2907)
= 0.02 + 0.01273
= 0.03273 V
The emf of the cell is 0.03273 V.
APPEARS IN
संबंधित प्रश्न
Choose the most correct option.
The standard potential of the cell in which the following reaction occurs:
H2 (g,1 atm) + Cu2+ (1M) → 2H+ (1M) + Cu(s),
`("E"_"Cu"^circ = 0.34 "V")` is
Answer the following in one or two sentences.
Write Nernst equation. What part of it represents the correction factor for nonstandard state conditions?
Answer the following in one or two sentences.
Under what conditions the cell potential is called standard cell potential?
Answer the following:
Predict whether the following reaction would occur spontaneously under standard state condition.
`"Ca"_(("s")) + "Cd"_(("aq"))^(2+) -> "Ca"_(("aq"))^(2+) + "Cd"_(("s"))`
Answer the following:
Predict whether the following reaction would occur spontaneously under standard state condition.
`2"Br"_(("aq"))^(-) + "Sn"_(("aq"))^(2+) -> "Br"_(2("l")) + "Sn"_(("s"))`
What is cell voltage?
Calculate `"E"_"cell"^circ` of the following galvanic cell:
Mg(s) / Mg2+(1 M) // Ag+ (1 M) / Ag(s) if `"E"_"Mg"^circ` = – 2.37 V and `"E"_"Ag"^circ` = 0.8 V. Write cell reactions involved in the above cell. Also mention if cell reaction is spontaneous or not.
Standard reduction electrode potentials of three metals A, B and C are +0.5 V, −3.0 V and −1.2 V respectively. The reducing power of these metals is ______.
Calculate E.M.F. of following cell at 298 K Zn(s) |ZnSO4 (0.01 M)| |CuSO4 (1.0 M)| Cu(s) if \[\ce{E^0_{cell}}\] = 2.0 V.
Calculate \[\ce{E^0_{cell}}\] for the following cell.
\[\ce{Cr_{(s)} | Cr^{3+}_{( aq)} || Fe^{2+}){( aq)} | Fe_{(s)}}\]
Given: `"E"_("Cr"^(3+)//"Cr")^0` = −0.74 V,
`"E"_("Fe"^(2+)//"Fe")^0` = −0.44 V
The reduction potential of a half-cell consisting of nickel electrode in 0.1 M NiSO4 solution at 25°C is ____________.
(E0 = −0.257 V)
Identify the strongest reducing agent from the data given below:
| Element | `"E"^0 ("V")` |
| Al | −1.66 |
| Fe | −0.44 |
| Hg | +0.79 |
| Cu | +0.337 |
What is the standard emf of the following cell?
\[\ce{Ni_{(s)} | Ni^{2+}_{( aq)} || Au^{3+}_{( aq)} | Au_{(s)}}\]
if \[\ce{E^0_{Ni}}\] = −0.25 V, \[\ce{E^0_{Au}}\] = 1.50 V.
For the following cell, standard potential of copper electrode is 0.337 V and standard cell potential is 0.463 V.
\[\ce{Cu | Cu^{2+} (1 M) || Ag^+ (1 M) Ag}\]
What is the standard potential of silver electrode?
What is the standard potential of cell, Ni | Ni2+ (1M) || Cu2+ (1 M) | Cu?
If E°Cu = 0.337 V and E°Ni = - 0.236 V.
Answer the following in one or two sentences.
What is the standard cell potential for the reaction?
\[\ce{2Al(s) + 3Ni^{2⊕}(1M) -> 2Al^{3⊕}(1 M) + 3Ni(s)}\]
if \[\ce{E{^{\circ}_{Ni}}}\] = −0.25 V and \[\ce{E{^{\circ}_{Al}}}\] = −1.66 V?
The standard EMF for the cell reaction,
\[\ce{Zn + Cu^{2+} -> Zn^{2+} + Cu}\],
is 1.10 V at 25°C. The EMF of the cell reaction, when 0.1 M Cu2+ and 0.1 M Zn2+ solutions are used at 25°C is:
Construct a cell from Ni2+ | Ni and Cu2+ | Cu Cu half cells. Write the cell reaction and calculate `E_("cell")^0`
`(E_("Ni")^0 = - 0.236 V and E_("Cu")^0 = + 0.337 V)`
The standard potential of the electrode Zn2+(0.02M) |Zn(s) is − 0.76 V. Calculate the electrode potential of the zinc electrode.
Write net cell reaction.
Standard potential (E°) of
\[\mathrm{Zn_{(aq)}^{+2}+2e^{-}\longrightarrow Zn_{(s)}~is~-0.76~V}\]
What is standard potential of reaction
\[2\mathrm{Zn}_{(\mathrm{s})}\longrightarrow2\mathrm{Zn}_{(\mathrm{aq})}^{+2}+4\mathrm{e}^{-}\] ?
Which from following formulae is used to obtain value of E°cell for a reaction taking place in Dry cell?
What is the reduction potential of hydrogen gas electrode when pure hydrogen gas is at 1 atmosphere pressure and platinum electrode is in contact with HCI of pH 2 at 298 K?
