which half - reaction correctly describes an oxidation?\nca(s)+2e^−⟶ca^{2 + }(aq)\nbr_2 + 2e^−⟶2br^−\nna^{+}(…

which half - reaction correctly describes an oxidation?\nca(s)+2e^−⟶ca^{2 + }(aq)\nbr_2 + 2e^−⟶2br^−\nna^{+}(aq)⟶na(s)+e^−\ncr(s)⟶cr^{3 + }(aq)+3e^−

which half - reaction correctly describes an oxidation?\nca(s)+2e^−⟶ca^{2 + }(aq)\nbr_2 + 2e^−⟶2br^−\nna^{+}(aq)⟶na(s)+e^−\ncr(s)⟶cr^{3 + }(aq)+3e^−

Answer

Brief Explanations:

Oxidation is the loss of electrons. In the reaction $\text{Cr}(s)\longrightarrow\text{Cr}^{3 +}(aq)+3\text{e}^{-}$, chromium (Cr) loses 3 electrons to form $\text{Cr}^{3+}$ ion. In the other reactions, electrons are gained (reduction). For example, in $\text{Ca}(s)+2\text{e}^{-}\longrightarrow\text{Ca}^{2 +}(aq)$, calcium gains electrons, in $\text{Br}_2 + 2\text{e}^{-}\longrightarrow2\text{Br}^{-}$, bromine gains electrons and in $\text{Na}^{+}(aq)\longrightarrow\text{Na}(s)+\text{e}^{-}$, sodium ion gains an electron.

Answer:

$\text{Cr}(s)\longrightarrow\text{Cr}^{3 +}(aq)+3\text{e}^{-}$