Advertisements
Advertisements
प्रश्न
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
उत्तर
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
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
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 in one or two sentences.
Under what conditions the cell potential is called standard cell potential?
Answer the following in brief.
Construct a galvanic cell from the electrodes Co3+ | Co and Mn2+/Mn. \[\ce{E{^{\circ}_{Co}}}\] = 1.82 V, \[\ce{E{^{\circ}_{Mn}}}\] = –1.18 V. Calculate \[\ce{E{^{\circ}_{cell}}}\]
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
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 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 ______.
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 ΔG0 for the following reaction?
\[\ce{Al_{(s)} + Fe^{3+}_{( aq)} -> Al^{3+}_{( aq)} + Fe_{(s)}}\]; \[\ce{E^0_{cell}}\] = +2.43
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 standard electrode potential of Zn and Ni are - 0.76 V and - 0.25 V respectively. If the reaction takes place in the cell constructed between these two electrodes is spontaneous. What is the standard emf of the cell?
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)`
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.
Write the four applications of emf series.
Standard potential (E°) of
\[\mathrm{Zn_{(aq)}^{+2}+2e^{-}\longrightarrow Zn_{(s)}~is~-0.76~V}\]
What is standard potential of reaction
\[2\mathrm{Zn}_{(\mathrm{s})}\longrightarrow2\mathrm{Zn}_{(\mathrm{aq})}^{+2}+4\mathrm{e}^{-}\] ?
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?
