To determine which term best describes the given reaction:
[tex]\[ Sn^{4+}(aq) + 2 e^{-} \rightarrow Sn^{2+}(aq) \][/tex]
Let's analyze the reaction step-by-step:
1. Identification of species and their charges:
- On the left side of the reaction, we have the ion [tex]\( Sn^{4+} \)[/tex], which has a charge of +4.
- On the right side of the reaction, we have the ion [tex]\( Sn^{2+} \)[/tex], which has a charge of +2.
2. Electron transfer:
- The reaction involves the addition of 2 electrons ([tex]\( 2 e^{-} \)[/tex]) to the [tex]\( Sn^{4+} \)[/tex] ion.
- Electrons are negatively charged particles.
3. Charge changes:
- By gaining 2 electrons, the charge on the [tex]\( Sn \)[/tex] ion changes from +4 to +2.
- This change indicates a decrease in oxidation state from +4 to +2.
4. Defining the type of reaction:
- Oxidation involves the loss of electrons and an increase in oxidation state.
- Reduction involves the gain of electrons and a decrease in oxidation state.
- Ionization usually refers to the process in which atoms or molecules gain or lose electrons to form ions.
- Neutralization refers to a reaction between an acid and a base to form water and a salt.
Since the [tex]\( Sn^{4+} \)[/tex] ion gains 2 electrons, reducing its oxidation state from +4 to +2, this reaction is characterized by a gain of electrons and thus reduction.
Therefore, the correct term to describe this reaction is:
(4) reduction
The answer is 4.
