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When heated in air, the alkali metals fo...

When heated in air, the alkali metals form various oxides. Mention the oxides formed by `Li,Na` and K.

Text Solution

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The reactivity of alkali metals towards oxygen increases on moving down the group with the increase in atomic size. Thus, Li forms only lithium oxide `(Li_(2)O)`. Sodium forms mainly sodium peroxide `Na_(2)O_(2)` along with a small amount of sodium oxide while potassium forms only potassium superoxide `(KO_(2))`.
`4Li+O_(2) overset(Delta)rarr 2Li_(2)O`
`6Na+2O_(2)overset(Delta)rarr underset("Sodium peroxide"("major"))(Na_(2)O_(2)) + underset("Monoxide"("minor"))(2Na_(2)O)`
`K+O_(2)overset(Delta)rarr underset("Potassium super oxides")(KO_(2))+underset("Peroxide")(K_(2)O_(2))+underset("Monoxide")(K_(2)(O))`
The superoxide `O_(2)^(-)` ion is stable only in presence of large cations such as K.Rb etc.
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Name the alkali metals which form superoxides when heated in excess of air.

When heated in excess of air, alkali metals form different types of oxides depending upon the nature of the metal. Which of the following alkali metals form surperoxides ?

On heating lead nitrate forms oxides of nitrogen and lead. The oxides formed are :

The metal which form amphoteric oxide is

The number of alkali metals forming superoxides on heating with dioxygen is Li ,Na , K , Rb ,Cs

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Knowledge Check

  • When heated in excess of air, alkali metals form different types of oxides depending upon the nature of the metal. Which of the following alkali metals form surperoxides ?

    A
    All alkali metals except Li
    B
    All alkali metals except Li and Na
    C
    All alkali metals except Li, Na and K
    D
    All alkali metals except Fr

  • On heating lead nitrate forms oxides of nitrogen and lead. The oxides formed are :

    A
    `N_(2)O, PbO`
    B
    `NO_(2), PbO`
    C
    NO, PbO
    D
    `NO, PbO_(2)`

  • The metal which form amphoteric oxide is

    A
    iron
    B
    aluminium
    C
    sodium
    D
    calcium