Respuesta :
Oxygen, a chalcogen, has oxidation state 2-. Therefore, Cr is Cr2O7^2- has a charge of 6+. This charge becomes 0 after the reaction, so Cr gained electrons and was reduced. This also means that Cr2O7 was the oxidizing agent.
Meanwhile, since H has a charge of 1+, the oxidation state of C in C2H5OH is 2-. In the product CO2, its charge is 4+. This means that it lost electrons, and was oxidized. Therefore, ethanol (C2H5OH) is the reducing agent.
Meanwhile, since H has a charge of 1+, the oxidation state of C in C2H5OH is 2-. In the product CO2, its charge is 4+. This means that it lost electrons, and was oxidized. Therefore, ethanol (C2H5OH) is the reducing agent.
Explanation:
A redox equation is defined as an equation that shows reduction and oxidation are taking place simultaneously in a chemical reaction.
When electrons are lost in a chemical reaction then it is known as oxidation reaction. Whereas when electrons are gained in a chemical reaction then it is known as a redox reaction.
For example, [tex]Cr_{2}O^{2-}_{7} + C_{2}H_{5}OH \rightarrow Cr^{3+} + CO_{2}[/tex]
Reduction-half reaction: [tex]Cr_{2}O^{2-}_{7} + 3e^{-1} \rightarrow Cr^{3+}[/tex]
Oxidation state of Cr in [tex]Cr_{2}O^{2-}_{7}[/tex] is +6.
Oxidation-half reaction: [tex]C_{2}H_{5}OH \rightarrow CO_{2} + 6e^{-1}[/tex]
Oxidation state of C in [tex]C_{2}H_{5}OH[/tex] is -2 and in [tex]CO_{2}[/tex] oxidation state of C is +4.
Now, to balance the equation multiply reduction-half reaction by 2.
[tex]2Cr_{2}O^{2-}_{7} + 6e^{-1} \rightarrow 2Cr^{3+}[/tex]
Thus, the combined balanced chemical reaction equation will be as follows.
[tex]2Cr_{2}O^{2-}_{7} + C_{2}H_{5}OH \rightarrow 2Cr^{3+} + CO_{2}[/tex]
