Write down the dissociation reaction of acetic acid ($H_3O^+$ will be simplified by $H^+$)
$CH_3COOH$ $\rightarrow$ $CH_3COO^-$ $+$ $H^+$.
The reaction between acetic acid and magnesium is a redox reaction. Identify the oxidant and reductant!
Oxidant: $H^+$ Reductant: $Mg$
Write the redox reaction with the oxidant and reductant alone!
$2H^+$ $+$ $2e^-$ $\rightarrow$ $ H_2$
$Mg$ $-$ $2e^-$ $\rightarrow$ $ Mg^{2+}$
$2H^+$ $+$ $Mg$ $\rightarrow$ $ H_2$ $+$ $Mg^{2+}$
Write a nonionic simplified equation!
$CH_3COOH$ $+$ $Mg$ $\rightarrow$ $ H_2$ $+$ $(CH_3COO)_2Mg$ Production of colorless $H_2$ gas is observed and the dissolution in water of the reaction product, magnesium acetate.
Would we have a similar reaction with iron? copper?
$2H^+$ $+$ $2e^-$ $\rightarrow$ $ H_2$
$Fe$ $-$ $2e^-$ $\rightarrow$ $ Fe^{2+}$
$2H^+$ $+$ $Fe$ $\rightarrow $ $ H_2$ $+$ $Fe^{2+}$
No similar reaction with copper (see the → Redox table )