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Question
Consider the following standard electrode potential values:
\[\ce{Sn^{2+}_{ (aq)} + 2e^- -> Sn_{(s)}}\]; E0 = −0.14 V
\[\ce{Fe^{3+}_{ (aq)} + e^- -> Fe^{2+}_{ (aq)}}\]; E0 = +0.77 V
What is the cell reaction and potential for the spontaneous reaction that occurs?
Options
\[\ce{2Fe^{2+}_{ (aq)} + Sn^{2+}_{ (aq)} -> 2Fe^{3+}_{ (aq)} + Sn_{(s)}}\]; E0 = −0.91 V
\[\ce{2Fe^{3+}_{ (aq)} + Sn_{(s)} -> 2Fe^{2+}_{ (aq)} + Sn^{2+}_{ (aq)}}\]; E0 = +0.91 V
\[\ce{2Fe^{2+}_{ (aq)} + Sn^{2+}_{ (aq)} -> 2Fe^{3+}_{ (aq)} + Sn_{(s)}}\]; E0 = +0.91 V
\[\ce{2Fe^{3+}_{ (aq)} + Sn_{(s)} -> 2Fe^{3+}_{ (aq)} + Sn^{2+}_{ (aq)}}\]; E0 = +1.68 V
Solution
\[\ce{2Fe^{3+}_{ (aq)} + Sn_{(s)} -> 2Fe^{2+}_{ (aq)} + Sn^{2+}_{ (aq)}}\]; E0 = +0.91 V
Explanation:
Cell potential
\[\ce{E^0_{cell} = E^0_{cathode} - E^0_{anode}}\]
= +0.77 − (−0.14)
= +0.91 V
The cell reaction will be
\[\ce{2Fe^{3+}_{ (aq)} + Sn_{(s)} -> 2Fe^{2+}_{ (aq)} + Sn^{2+}_{ (aq)}}\]
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RELATED QUESTIONS
Why do interstitial compounds have higher melting points than corresponding pure metals?
Give reasons: E° value for the Mn3+/Mn2+ couple is much more positive than that for Fe3+/Fe2+.
Transition metals with lowest melting point is:
Read the passage given below and answer the following question:
The transition metals when exposed to oxygen at low and intermediate temperatures form thin, protective oxide films of up to some thousands of Angstroms in thickness. Transition metal oxides lie between the extremes of ionic and covalent binary compounds formed by elements from the left or right side of the periodic table. They range from metallic to semiconducting and deviate by both large and small degrees from stoichiometry. Since electron bonding levels are involved, the cations exist in various valence states and hence give rise to a large number of oxides. The crystal structures are often classified by considering a cubic or hexagonal close-packed lattice of one set of ions with the other set of ions filling the octahedral or tetrahedral interstices. The actual oxide structures, however, generally show departures from such regular arrays due in part to distortions caused by packing of ions of different size and to ligand field effects. These distortions depend not only on the number of d-electrons but also on the valence and the position of the transition metal in a period or group.
In the following questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices on the basis of the above passage.
Assertion: Transition metals form protective oxide films.
Reason: Oxides of transition metals are always stoichiometric.
Transition elements form binary compounds with halogens. Which of the following elements will form \[\ce{MF3}\] type compounds?
(i) \[\ce{Cr}\]
(ii) \[\ce{Co}\]
(iii) \[\ce{Cu}\]
(iv) \[\ce{Ni}\]
Match the properties given in Column I with the metals given in Column II.
| Column I (Property) | Column II (Metal) | |
| (i) | An element which can show +8 oxidation state | (a) \[\ce{Mn}\] |
| (ii) | 3d block element that can show | (b) \[\ce{Cr}\] |
| upto +7 oxidation state | (c) \[\ce{Os}\] | |
| (iii) | 3d block element with highest melting point | (d) \[\ce{Fe}\] |
Match the properties given in Column I with the metals given in Column II.
| Column I (Property) | Column II (Metal) | |
| (i) | Element with highest second ionisation enthalpy |
(a) \[\ce{Co}\] |
| (ii) | Element with highest third ionisation enthalpy |
(b) \[\ce{Cr}\] |
| (iii) | \[\ce{M}\] in \[\ce{M(CO)6}\] is | (c) \[\ce{Cu}\] |
| (iv) | Element with highest heat of atomisation |
(d) \[\ce{Zn}\] |
| (e) \[\ce{Ni}\] |
Account for the following:
Ce4+ is a strong oxidising agent.
Which one among the following metals of the 3d series has the lowest melting point?
Write the number of unpaired electrons in Cr3+.
(Atomic number of Cr = 24)
