Answer to Question #345842 in General Chemistry for Meg

Question

Balance the following equations, using the oxidization number method for the redox part of the equation. Show your work.

A. Cu2O(s) + H2(g) —> Cu(s) + H2O(l)

B. Cl2(g) + KBr(aq) —> Br2(l) + KCl(aq)

Answer 1

A.

we write the degree of oxidation on the top each element in the reaction equation:

Cu₂⁺O^2– + H₂⁰ = Cu⁰ + H₂⁺O^2–

we write the pre- and post-reaction states of elements with changed oxidation states and the number of electrons involved in its change:

Cu⁺ + 1 e^- —> Cu⁰ 1

H₂⁰ – 2 e- —> 2H⁺ 2

We write the number of electrons involved in the change of the first element as a coefficient for the second element. We write the number of electrons involved in the change of the second element as the coefficient of the first element:

Cu₂O + H₂ = 2 Cu + H₂O

B.

we write the degree of oxidation on the top each element in the reaction equation:

Cl₂⁰ + K⁺Br^– = Br₂⁰ + K⁺Cl^–

we write the pre- and post-reaction states of elements with changed oxidation states and the number of electrons involved in its change:

Cl₂⁰ + 2 e^- —> 2Cl^– 2

2 Br^– – 2 e^- —> Br₂⁰ 2

We write the number of electrons involved in the change of the first element as a coefficient for the second element. We write the number of electrons involved in the change of the second element as the coefficient of the first element:

Cl₂ + 2 KBr = Br₂ + 2 KCl