Question

decide whether each chemical reaction in the table below is an oxidation - reduction (
edox\) reaction. if the reaction is a redox reaction, write down the formula of the reducing agent and the formula of the oxidizing agent.

feo(s)+co(g)→fe(s)+co₂(g)

2h₂s(g)+o₂(g)→2s(s)+2h₂o(l)

na₂co₃(s)+h₃po₄(aq)→na₂hpo₄(aq)+co₂(g)+h₂o(l)

Explanation:

Step1: Determine if it is a redox reaction

A redox reaction is a chemical reaction in which there is a transfer of electrons, which can be identified by a change in oxidation states of elements.

• For \(FeO(s)+CO(g)\to Fe(s)+CO_{2}(g)\):
• In \(FeO\), the oxidation state of \(Fe\) is \(+ 2\), and in \(Fe\) (elemental form) it is \(0\). The oxidation state of \(C\) in \(CO\) is \(+2\), and in \(CO_{2}\) it is \(+4\). Since there are changes in oxidation states, it is a redox reaction.
• For \(2H_{2}S(g)+O_{2}(g)\to 2S(s)+2H_{2}O(l)\):
• In \(H_{2}S\), the oxidation state of \(S\) is \(-2\), and in \(S\) (elemental form) it is \(0\). The oxidation state of \(O\) in \(O_{2}\) is \(0\), and in \(H_{2}O\) it is \(-2\). Since there are changes in oxidation states, it is a redox reaction.
• For \(Na_{2}CO_{3}(s)+H_{3}PO_{4}(aq)\to Na_{2}HPO_{4}(aq)+CO_{2}(g)+H_{2}O(l)\):
• Check the oxidation states of all elements: \(Na = + 1\), \(C=+4\), \(O=-2\), \(H = + 1\), \(P=+5\) in all compounds. There is no change in oxidation states, so it is not a redox reaction.

Step2: Identify reducing and oxidizing agents

• For \(FeO(s)+CO(g)\to Fe(s)+CO_{2}(g)\):
• The substance that is oxidized (loses electrons, increases in oxidation state) is the reducing agent. \(CO\) is oxidized (\(C\) from \(+2\) to \(+4\)), so \(CO\) is the reducing agent.
• The substance that is reduced (gains electrons, decreases in oxidation state) is the oxidizing agent. \(FeO\) is reduced (\(Fe\) from \(+2\) to \(0\)), so \(FeO\) is the oxidizing agent.
• For \(2H_{2}S(g)+O_{2}(g)\to 2S(s)+2H_{2}O(l)\):
• \(H_{2}S\) is oxidized (\(S\) from \(-2\) to \(0\)), so \(H_{2}S\) is the reducing agent.
• \(O_{2}\) is reduced (\(O\) from \(0\) to \(-2\)), so \(O_{2}\) is the oxidizing agent.

Answer:

• For \(FeO(s)+CO(g)\to Fe(s)+CO_{2}(g)\):
• redox reaction? yes
• reducing agent: \(CO\)
• oxidizing agent: \(FeO\)
• For \(2H_{2}S(g)+O_{2}(g)\to 2S(s)+2H_{2}O(l)\):
• redox reaction? yes
• reducing agent: \(H_{2}S\)
• oxidizing agent: \(O_{2}\)
• For \(Na_{2}CO_{3}(s)+H_{3}PO_{4}(aq)\to Na_{2}HPO_{4}(aq)+CO_{2}(g)+H_{2}O(l)\):
• redox reaction? no
• reducing agent: (not applicable)
• oxidizing agent: (not applicable)