Question

Which metal oxides are acidic?

Answer 1

Metals oxides are acidic: Transition metal oxides in their higher oxidation states are acidic. Mn and Cr form acidic oxides in their higher oxidation states.

• Manganese heptoxide$\left(M{n}_2{O}_7\right)$ forms permanganic acid $\left(HMn{O}_4\right)$
• Chromium trioxide$\left(Cr{O}_3\right)$ forms chromic acid$\left(H_{2}Cr{O}_4\right)$
• Manganese heptoxide and Chromium trioxide are acidic oxides.
• The oxidation number of$MninM{n}_2{O}_{7}is+7$ (highest oxidation number of Mn)
• The oxidation number of $CrinCr{O}_{3}is+6$ (highest oxidation number of Cr).
• Hence, $\left(M{n}_2{O}_7\right)$ and $\left(Cr{O}_3\right)$ metal oxides are acidic.