Advertisements
Advertisements
Question
Answer the following:
Calculate emf of the cell:
Zn(s) |Zn2+ (0.2 M)||H+ (1.6 M)| H2(g, 1.8 atm)| Pt at 25 °C.
Advertisements
Solution
Given: [Zn2+] = 0.2 M, [H+] = 1.6 M, `"P"_("H"_2)` = 1.8 atm
To find: Emf of the cell `("E"_"cell")`
Formulae:
1) `"E"_"cell"^circ = "E"_"cathode"^circ - "E"_"anode"^circ`
2) `"E"_"cell" = "E"_"cell"^circ - (0.0592 "V")/"n" log_10 [["Product"]]/[["Reactant"]]`
Calculation:
`"Zn"_(("s")) -> "Zn"_((0.2 "M"))^(2+) + 2"e"^(-)` (oxidation at anode)
`2"H"_((1.6 "M"))^+ + 2"e"^(-) -> "H"_(2(1.8 "atm"))` (reduction at cathode)
___________________________________________________
`"Zn"_(("s")) + 2"H"_((1.6 "M"))^+ -> "Zn"_((0.2 "M"))^(2+) + "H"_(2(1.8 "atm"))` (overall reaction)
`"E"_("H"_2)^circ = 0.0 "V" and "E"_("Zn")^circ` = - 0.763 V
Using formula (i),
`"E"_"cell"^circ = "E"_"cathode"^circ - "E"_"anode"^circ`
`"E"_"cell" = "E"_("H"_2)^circ - "E"_("Zn")^circ`
= 0.0 V - (- 0.763 V) = 0.769 V
Using formula (ii),
The cell potential is given by
`"E"_"cell" = "E"_"cell"^circ - (0.0592 "V")/2 log_10 [["Product"]]/[["Reactant"]]`
= 0.763 - `(0.0592 "V")/2 log_10 ((0.2)(1.8))/(1.6)^2`
= 0.763 + 0.0252 = 0.7882 V
The emf of the cell is 0.7882 V.
APPEARS IN
RELATED QUESTIONS
Consider the half reactions with standard potentials.
- \[\ce{Ag^{\oplus}_{ (aq)} + e^{\ominus} -> Ag_{(s)}E^\circ = 0.8 V}\]
- \[\ce{I2_{(s)} + 2e^\ominus -> 2I^{\ominus}_{(aq)} E^\circ = 0.53V}\]
- \[\ce{Pb^{2\oplus}_{(aq)} + 2e^{\ominus} -> Pb_{(s)} E^\circ = -0.13 V}\]
- \[\ce{Fe^{2\oplus} + 2e^{\ominus} -> Fe_{(s)} E^\circ = -0.44 V}\]
The strongest oxidising and reducing agents respectively are ______.
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:
Predict whether the following reaction would occur spontaneously under standard state condition.
`"Ca"_(("s")) + "Cd"_(("aq"))^(2+) -> "Ca"_(("aq"))^(2+) + "Cd"_(("s"))`
What is cell voltage?
Calculate the voltage of the cell Sn(s) / Sn2+(0.02 M) // Ag+ (0.01 M) / Ag(s) at 25 °C.
Given: `"E"_"Sn"^circ` = - 0.136, `"E"_"Ag"^circ` = 0.800 V
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 ______.
The correct representation of Nernst's equation for half-cell reaction \[\ce{Cu^{2+} (aq) + e^- -> Cu^+(aq)}\] 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
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.
The tendency of an electrode to lose electrons is known as ______
The standard potential of the cell in the following reaction is ______.
\[\ce{Cd_{(s)} + Cu^{2+}_{(1M)} -> Cd^{2+}_{(1M)} + Cu_{(s)}}\]
`("E"_("Cd")^circ = - 0.403V, "E"_("Cu")^circ = 0.334V)`
Which element from the following has the highest negative standard reduction potential?
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)`
Calculate the emf of the following cell at 25°C.
Zn(s)|Zn2+(0.08 M) || Cu2+(0.l M) |Cu(s)
E0zn = − 0.76 V, E0cu = 0.36 V.
Write the value of `(2.303 RT)/F` in the Nernst equation?
Write the four applications of emf series.
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?
Which from following is CORRECT expression for Ecell of following cell?
\[\ce{Pb_{(s)} | Pb^++_{(1 m)} || Ag^+_{(0.1 m)} | Ag_{(g)}}\] at 25°C?
