Reaction of ethanol with sodium

Experiment

In ethanol sodium "dissolves" (= becomes a soluble substance, namely sodium ethanolate), evolving hydrogen.

Oxidation numbers (Oxidation states OS)

The H atom has a different oxidation number in ethanol than in $H_2$:

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Reminder: Oxidation numbers are determined by attributing to the more electronegative atoms all electrons of the covalent bond, and are equal to the dummy load thus obtained.

Partial redox system

Redox reactions

$2CH_3CH_2OH$ $+$ $2e^-$ $\rightarrow$ $ CH_3CH_2O^-$ $+$ $H_2$ $2Na$ $-$ $2e^-$ $\rightarrow$ $2Na^+$ | $\cdot 2$ $2CH_3CH_2OH$ $+$ $2Na$ $\rightarrow$ $ 2CH_3CH_2O^-$ $ +$ $2Na^+$ $+$ $H_2$ This reaction is sometimes interpreted as due to an "acidic" character ethanol. It is initiated by a first acid dissociation of the molecule followed by reaction of the ion $H^+$ formed with sodium:: $2CH_3CH_2OH$ $\rightarrow$ $ 2CH_3CH_2O^-$ $+$ $2H^+$ then: $2H^+$ $+$ $2e^-$ $\rightarrow$ $ H_2$ $2Na$ $-$ $2e^-$ $\rightarrow$ $2Na^+$ $2H^+$ $+$ $2Na$ $\rightarrow$ $ 2Na^+$ $+$ $H_2$ Sodium ethanolate such formed is colorless and soluble in ethanol: