A base $B$ is strong if its proton exchange reaction with water (dissociation) producing the corresponding acide $HB$ $B$ $+$ $H_2O$ $\rightarrow$ $ OH^-$ $+$ $HB$ is complete.
- Note the single arrow reaction $\rightarrow$ - Eventual charges of $HB$ and $B$ are not shown in this general formula
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| $NH_2^-$ | amide |
| $RO^-$ | alcoolate (R = methyl, ethyl..) |
| $O^{2-}$ | oxide (from soluble oxides) |
The dissociation reactions of these bases: $NH_2^-$ $+$ $H_2O$ $\rightarrow$ $ OH^-$ $+$ $NH_3$ $CH_3O^-$ $+$ $H_2O$ $\rightarrow$ $ OH^-$ $+$ $CH_3OH$ $C_2H_5O^-$ $+$ $H_2O$ $\rightarrow$ $ OH^-$ $+$ $C_2H_5OH$ $O^{2-}$ $+$ $H_2O$ $\rightarrow$ $2$$OH^-$
Assimilated to strong bases: The soluble hydroxides $Me(OH)_x$ (with Me= Li,Na,K,..x = 1, 2,..)
In this case, the hydroxide ions come from the simple dissociation in water, such: $NaOH$ $\rightarrow$ $ OH^-$ $+$ $Na^+$ (Sodium hydroxide produces sodium ion and hydroxide ion ) $Mg(OH)_2 $ $\rightarrow$ $2$$OH^-$ $+$ $Mg^{2+}$ (Magnesium hydroxyide produces magnesium ion and hydroxide ion)