Search:   
 

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 $H_2$:

Click the image !

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

Ethanol $\Rightarrow$ ethanolate and hydrogen: $2CH_3CH_2OH$ $+$ $2e^-$ $\rightarrow$ $ 2CH_3CH_2O^-$ $+$ $H_2$

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: