Question

in the following reaction, how many electrons are exchanged between the reactants?
mn(s) + 2ag⁺(aq) → mn²⁺(aq) + 2ag(s)
○ 2
○ 3
○ 1
○ 6
○ zero. this isnt a redox reaction.
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question 18
which of the following statements is true?
○ reduction is the loss of electrons. when reduced, electrons appear on the products side of a half-reaction.
○ reduction is the gain of electrons. when reduced, electrons appear on the products side of a half-reaction.
○ reduction is the gain of electrons. when reduced, electrons appear on the reactants side of a half reaction.
○ oxidation is the gain of electrons. when oxidized, electrons appear on the products side of a half reaction
○ oxidation is the loss of electrons. when oxidized, electrons appear on the reactants side of a half reaction

Explanation:

First Sub - Question (Electron Exchange in Reaction)

Step1: Analyze Mn's oxidation state change

Mn starts as \(Mn(s)\) with an oxidation state of 0. It becomes \(Mn^{2 + }(aq)\), so the change in oxidation state is \(0
ightarrow+ 2\). This means Mn loses 2 electrons (since oxidation is loss of electrons).

Step2: Analyze Ag's oxidation state change

\(Ag^{+}(aq)\) has an oxidation state of + 1. It becomes \(Ag(s)\) with an oxidation state of 0. For 2 moles of \(Ag^{+}\), each \(Ag^{+}\) gains 1 electron, so total electrons gained is \(2\times1 = 2\) electrons. The number of electrons lost by Mn equals the number of electrons gained by Ag, so the number of electrons exchanged is 2.

• Option 1: Reduction is gain (not loss) of electrons. In a reduction half - reaction, electrons are on the reactants side (since the species is gaining electrons), so this is wrong.
• Option 2: Reduction is gain of electrons, but in a reduction half - reaction, electrons are on the reactants side (e.g., \(Ag^{+}+e^{-}

ightarrow Ag\)), not products side, so wrong.

• Option 3: Reduction is gain of electrons. In a reduction half - reaction (e.g., \(Cu^{2+}+2e^{-}

ightarrow Cu\)), electrons are on the reactants side as the species is gaining them. This is correct.

• Option 4: Oxidation is loss (not gain) of electrons, so this is wrong.
• Option 5: Oxidation is loss of electrons, and in an oxidation half - reaction (e.g., \(Zn

ightarrow Zn^{2+}+2e^{-}\)), electrons are on the products side, not reactants side, so wrong.

Answer:

2

Second Sub - Question (True Statement about Redox)