Q23E - Chemistry (OpenStax)

Question

Complete and balance each of the following oxidation-reduction reactions,such that it results in the highest possible oxidation state for the oxidized atoms.

(a) \(Al\left( s \right) + {F_2}\left( g \right) \to \)

(b) \(Al\left( s \right) + CuB{r_2}\left( {aq} \right) \to \)  (single displacement)

(c) \({P_4}\left( s \right) + {O_2}\left( g \right) \to \)

(d) \(Ca\left( s \right) + {H_2}O\left( l \right) \to \) (products are a strong base and a diatomic gas)

Step-by-Step Solution

Answer

(a) \(2Al\left( s \right) + 3{F_2}\left( g \right) \to 2Al{F_3}\left( s \right)\)

(b) \(2Al\left( s \right) + 3CuB{r_2}\left( {aq} \right) \to 2AlB{r_3}\left( {aq} \right) + 3Cu\left( s \right)\)

(c) \({P_4}\left( s \right) + 5{O_2}\left( g \right) \to {P_4}{O_{10}}\left( s \right)\)

(d) \(Ca\left( s \right) + 2{H_2}O\left( l \right) \to Ca{\left( {OH} \right)_2}\left( s \right) + {H_2}\left( g \right)\).

Step 1: Formation of aluminium fluoride(a)

\(2Al\left( s \right) + 3{F_2}\left( g \right) \to 2Al{F_3}\left( s \right)\)

Aluminium is oxidised from 0 to +3 state and fluorine is reduced from 0 to -1 state.

Step 2: Formation of aluminium bromide(b)

\(2Al\left( s \right) + 3CuB{r_2}\left( {aq} \right) \to 2AlB{r_3}\left( {aq} \right) + 3Cu\left( s \right)\)

Aluminium is oxidised from 0 to +3 state and copper is reduced from +2 to 0 state.

Step 3: Formation of phosphorous pentoxide(c)

\({P_4}\left( s \right) + 5{O_2}\left( g \right) \to {P_4}{O_{10}}\left( s \right)\)

Phosphorus is oxidised from 0 to +4 state and oxygen is reduced from 0 to -2 state.

Step 4: Formation of calcium hydroxide(d)

\(Ca\left( s \right) + 2{H_2}O\left( l \right) \to Ca{\left( {OH} \right)_2}\left( s \right) + {H_2}\left( g \right)\)

Calcium is oxidised from 0 to +2 state and hydrogen reduced from +1 to 0 state.