Hydrazine is somewhat toxic. Use the following half-reactions to explain why household bleach (highly alkaline solutions of sodium hypochlorite) should not be mixed with household ammonia or glass cleansers that contain ammonia. $$ \mathrm{ClO}^{-}+\mathrm{H}_{2} \mathrm{O}+2 \mathrm{e}^{-} \longrightarrow 2 \mathrm{OH}^{-}+\mathrm{Cl}^{-} \quad \mathscr{E}^{\circ}=0.90 \mathrm{V} $$ $$ \mathrm{N}_{2} \mathrm{H}_{4}+2 \mathrm{H}_{2} \mathrm{O}+2 \mathrm{e}^{-} \longrightarrow 2 \mathrm{NH}_{3}+2 \mathrm{OH}^{-} \quad \mathscr{E}^{\circ}=-0.10 \mathrm{V} $$

We are given two half-reactions: \( \mathrm{ClO}^{-}+\mathrm{H}_{2} \mathrm{O}+2 \mathrm{e}^{-} \longrightarrow 2 \mathrm{OH}^{-}+\mathrm{Cl}^{-} \quad \mathscr{E}^{\circ}=0.90 \mathrm{V} \) \( \mathrm{N}_{2} \mathrm{H}_{4}+2 \mathrm{H}_{2} \mathrm{O}+2 \mathrm{e}^{-} \longrightarrow 2 \mathrm{NH}_{3}+2 \mathrm{OH}^{-} \quad \mathscr{E}^{\circ}=-0.10 \mathrm{V} \) Note that both half-reactions are already balanced in terms of mass and charge.

Since the number of electrons transferred in both half-reactions is equal (2 electrons), we can add the two half-reactions directly: \[ \begin{aligned} \mathrm{ClO}^{-}+\mathrm{H}_{2} \mathrm{O}+2 \mathrm{e}^{-} & \longrightarrow 2 \mathrm{OH}^{-}+\mathrm{Cl}^{-} \\ \mathrm{N}_{2} \mathrm{H}_{4}+2 \mathrm{H}_{2} \mathrm{O}+2 \mathrm{e}^{-} & \longrightarrow 2 \mathrm{NH}_{3}+2 \mathrm{OH}^{-} \end{aligned} \] Adding the half-reactions, the final redox reaction is: \[ \mathrm{ClO}^{-}+\mathrm{N}_{2} \mathrm{H}_{4}+3 \mathrm{H}_{2} \mathrm{O} \longrightarrow 2 \mathrm{NH}_{3}+2 \mathrm{OH}^{-}+\mathrm{Cl}^{-} \]

In the reaction obtained in Step 2, when household bleach (sodium hypochlorite) is mixed with ammonia or cleansers containing ammonia (in the form of hydrazine), the product formed is ammonia (\(\mathrm{NH}_3\)) and hydroxide ions (\(\mathrm{OH}^-\)). However, the presence of hydroxide ions in the reaction mixture may lead to the formation of toxic chloramine gas (\(\mathrm{NH}_2\mathrm{Cl}\)) and nitrogen trichloride (\(\mathrm{NCl}_3\)) as side reactions. These compounds are toxic and can cause respiratory irritation. Therefore, based on the full redox reaction and the possible side products formed, it is not recommended to mix household bleach with ammonia or glass cleansers containing ammonia due to the possible formation of toxic chemical species.