To determine which chemical equation represents a redox reaction, we need to check for changes in oxidation states of the elements involved in each reaction. A redox (oxidation-reduction) reaction involves the transfer of electrons between two species, leading to a change in their oxidation states.
Let's analyze each option:
### Option A:
[tex]\[ Mg(ClO_3)_2 + 2HCl \rightarrow MgCl_2 + 2HClO_3 \][/tex]
- Oxidation States:
- Magnesium (Mg) in [tex]\( Mg(ClO_3)_2 \)[/tex] and [tex]\( MgCl_2 \)[/tex]: 0
- Chlorine (Cl) changes from [tex]\( +5 \)[/tex] in [tex]\( ClO_3^- \)[/tex] and remains [tex]\( -1 \)[/tex] in [tex]\( HCl \)[/tex]
- Hydrogen (H) remains [tex]\( +1 \)[/tex]
- Oxygen (O) remains [tex]\( -2 \)[/tex]
Since there is no overall change in oxidation states, this is not a redox reaction.
### Option B:
[tex]\[ CO + H_2O \rightarrow H_2 + CO_2 \][/tex]
- Oxidation States:
- Carbon (C) in [tex]\( CO \)[/tex] is [tex]\( +2 \)[/tex]
- Carbon (C) in [tex]\( CO_2 \)[/tex] is [tex]\( +4 \)[/tex]
- Hydrogen (H) in [tex]\( H_2O \)[/tex] is [tex]\( +1 \)[/tex]
- Hydrogen (H) in [tex]\( H_2 \)[/tex] is [tex]\( 0 \)[/tex]
- Oxygen (O) remains [tex]\( -2 \)[/tex]
Carbon is oxidized (its oxidation state increases from [tex]\( +2 \)[/tex] to [tex]\( +4 \)[/tex]) and hydrogen is reduced (its oxidation state decreases from [tex]\( +1 \)[/tex] to [tex]\( 0 \)[/tex]).
This indicates a transfer of electrons, so this is a redox reaction.
### Option C:
[tex]\[ 2NH_4NO_3 + CuCl_2 \rightarrow 2NH_4Cl + Cu(NO_3)_2 \][/tex]
- Oxidation States:
- Nitrogen (N) in [tex]\( NH_4NO_3 \)[/tex] and [tex]\( NH_4Cl \)[/tex] remains unchanged
- Copper (Cu) in [tex]\( CuCl_2 \)[/tex] and [tex]\( Cu(NO_3)_2 \)[/tex] remains [tex]\( +2 \)[/tex]
- Chlorine (Cl) in [tex]\( CuCl_2 \)[/tex] and [tex]\( NH_4Cl \)[/tex] remains [tex]\( -1 \)[/tex]
- Oxygen (O) remains [tex]\( -2 \)[/tex]
There are no changes in oxidation states of the elements. This is not a redox reaction.
### Option D:
[tex]\[ Na_2SO_3 + FeBr_2 \rightarrow 2NaBr + FeSO_3 \][/tex]
- Oxidation States:
- Sodium (Na) remains [tex]\( +1 \)[/tex]
- Sulfur (S) in [tex]\( Na_2SO_3 \)[/tex] and [tex]\( FeSO_3 \)[/tex] remains [tex]\( +4 \)[/tex]
- Iron (Fe) in [tex]\( FeBr_2 \)[/tex] and [tex]\( FeSO_3 \)[/tex] remains [tex]\( +2 \)[/tex]
- Bromine (Br) in [tex]\( FeBr_2 \)[/tex] and [tex]\( NaBr \)[/tex] remains [tex]\( -1 \)[/tex]
- Oxygen (O) remains [tex]\( -2 \)[/tex]
Since there are no changes in the oxidation states of any elements, this is not a redox reaction.
### Conclusion:
The chemical equation that represents a redox reaction is:
[tex]\[ \text{B. } CO + H_2O \rightarrow H_2 + CO_2 \][/tex]
