Under strongly acidic conditions

CHEMISTRY · Multi-part · CBSE · Chemistry · Redox Reactions · Redox Reactions

Problem

Under strongly acidic conditions, ethanol is oxidized by dichromate according to the unbalanced ionic equation below:  C2H5OH(aq)+Cr2O72−(aq)+H+(aq)  ⟶  CH3COOH(aq)+Cr3+(aq)+H2O(ℓ)\mathrm{\,C_{2}H_{5}OH(aq)+Cr_{2}O_{7}^{2-}(aq)+H^{+}(aq)\;\longrightarrow\;CH_{3}COOH(aq)+Cr^{3+}(aq)+H_{2}O(\ell)} A chemist obtains the fully balanced equation shown here: 3 C2H5OH+2 Cr2O72−+16 H+→3 CH3COOH+4 Cr3++11 H2O\mathrm{3\,C_{2}H_{5}OH+2\,Cr_{2}O_{7}^{2-}+16\,H^{+}\rightarrow 3\,CH_{3}COOH+4\,Cr^{3+}+11\,H_{2}O} (1) Assign oxidation numbers to carbon in ethanol and acetic acid, and to chromium in Cr2O72−\mathrm{Cr_{2}O_{7}^{2-}} and Cr3+\mathrm{Cr^{3+}}. Show your work. (2) Identify the species that is oxidized and the species that is reduced. State the change in oxidation number for each process. (3) Using the balanced equation, calculate the number of moles of electrons transferred per mole of ethanol consumed. Show how electron conservation is satisfied. (4) Classify all reaction types that apply to this process and justify each classification with explicit reference to your findings in parts (a)–(c).

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