# Which equation is a redox process?

## $1.$ $N a B r \left(a q\right) + H C l \left(a q\right) r i g h t \le f t h a r p \infty n s N a C l \left(a q\right) + H B r \left(a q\right)$ $2.$ $H B r \left(a q\right) + A g N {O}_{3} \left(a q\right) \rightarrow A g B r \left(s\right) \downarrow + H N {O}_{3} \left(a q\right)$ $3.$ ${H}_{2} \left(g\right) + B {r}_{2} \left(g\right) \rightarrow 2 H B r \left(g\right)$ $4.$ $2 N a O H \left(a q\right) + {H}_{2} S {O}_{4} \left(a q\right) \rightarrow N {a}_{2} S {O}_{4} \left(a q\right) + 2 {H}_{2} O \left(l\right)$

Jun 20, 2016

Only $\left(3\right)$ exhibits redox, formal electron transfer.

#### Explanation:

$N a B r \left(a q\right) + H C l \left(a q\right) r i g h t \le f t h a r p \infty n s N a C l \left(a q\right) + H B r \left(a q\right)$

$H B r \left(a q\right) + A g N {O}_{3} \left(a q\right) \rightarrow A g B r \left(s\right) \downarrow + H N {O}_{3} \left(a q\right)$

${H}_{2} \left(g\right) + B {r}_{2} \left(g\right) \rightarrow 2 H B r \left(g\right)$

In this reaction zerovalent bromine oxidizes zerovalent hydrogen to give ${H}^{I +} B {r}^{- I}$ as the redox product.

$2 N a O H \left(a q\right) + {H}_{2} S {O}_{4} \left(a q\right) \rightarrow N {a}_{2} S {O}_{4} \left(a q\right) + 2 {H}_{2} O \left(l\right)$