Question

question 27
which of the following is a reduction half - reaction?
na ----> na+ + e-
no + 2h2o ----> n3 - + 4h+ + 3e-
zn ----> zn2+ + 2e-
2h+ + 2e- ----> h2
question 28
use the following reaction to answer the questions below:
ca + n2 --> ca3n2
which element was reduced select
which element was oxidized select
which element is the oxidizing agent? select

Explanation:

Step1: Recall reduction - oxidation rules

Reduction is the gain of electrons and a decrease in oxidation state. Oxidation is the loss of electrons and an increase in oxidation state. The oxidizing agent is the species that causes oxidation and is itself reduced.

Step2: Analyze Question 27

• For \(Na

ightarrow Na^{+}+e^{-}\), sodium loses an electron, it is an oxidation half - reaction.

• For \(NO + 2H_{2}O

ightarrow N_{3}^{-}+4H^{+}+3e^{-}\), nitrogen's oxidation state changes in an oxidation - like process (increase in oxidation number considering the overall change).

• For \(Zn

ightarrow Zn^{2 +}+2e^{-}\), zinc loses electrons, it is an oxidation half - reaction.

• For \(2H^{+}+2e^{-}

ightarrow H_{2}\), hydrogen ions gain electrons, it is a reduction half - reaction.

Step3: Analyze Question 28

• In the reaction \(Ca + N_{2}

ightarrow Ca_{3}N_{2}\), calcium has an oxidation state of 0 in elemental form and + 2 in \(Ca_{3}N_{2}\). Nitrogen has an oxidation state of 0 in \(N_{2}\) and - 3 in \(Ca_{3}N_{2}\).

• Calcium loses electrons (oxidation state increases from 0 to + 2), so calcium is oxidized.
• Nitrogen gains electrons (oxidation state decreases from 0 to - 3), so nitrogen is reduced. The oxidizing agent is the species that gets reduced, so nitrogen (\(N_{2}\)) is the oxidizing agent.

Answer:

Question 27: \(2H^{+}+2e^{-}
ightarrow H_{2}\)
Question 28:
Which element was reduced: Nitrogen
Which element was oxidized: Calcium
Which element is the oxidizing agent: Nitrogen