The unbalanced redox reaction

$$\ce{Mn^2+ + Cr2O7^2- -> Mn^3+ + Cr^3+}$$

occurs in what type of condition?

(a) Acidic
(b) Basic
(c) Neutral
(d) Indeterminable

  • $\begingroup$ Guess that would happen in any conditions. $\endgroup$ Oct 12 '19 at 19:29
  • $\begingroup$ Or perhaps in no conditions at all :D Depends on perspective... Presence of dichromate should be a dead giveaway for what answer is expected, though. $\endgroup$
    – Mithoron
    Oct 12 '19 at 20:36
  • 1
    $\begingroup$ So is the fact that they put $\ce{Mn^{3+}}$. Would not expect most trivalent ions to remain in solution when it's a_i. $\endgroup$ Oct 12 '19 at 22:57

$$\ce{Mn^{2+} + Cr2O7^{2-} -> Mn^{3+} + Cr^{3+}}$$

If you were to balance this reaction, using the appropriate molecules of water and protons, you'd get:

$$\ce{ Mn^{2+} + Cr2O7^{2-} + 14H+ + 5e- -> Mn^{3+} + 2Cr^{3+} + 7H2O }$$

The presence of protons the left side of equation suggests that this reaction has a higher rate when the concentration of protons is higher. That is, it is favored under acidic conditions.

  • 3
    $\begingroup$ With all due respect please avoid answering homework questions (even a one that is somewhat interesting to some extent, as this one) because this would encourage OP to post more textbook questions without bothering to make an attempt towards solving it (and they did). Also, showing intermediate steps in obtaining final equation would make it a better answer as now for the untrained chemist it probably looks similar to the tutorial for drawing an owl:) $\endgroup$
    – andselisk
    Oct 13 '19 at 3:28

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