Which two of the following reactions are oxidationreduction...

Which two of the following reactions are oxidationreduction reactions? Explain your answer in each case. Classify the remaining reaction. (a) $\mathrm{Zn}(\mathrm{s})+2 \mathrm{NO}_{3}^{-}(\mathrm{aq})+4 \mathrm{H}_{3} \mathrm{O}^{+}(\mathrm{aq}) \rightarrow$ $\mathrm{Zn}^{2+}(\mathrm{aq})+2 \mathrm{NO}_{2}(\mathrm{g})+6 \mathrm{H}_{2} \mathrm{O}(\ell)$ (b) $\mathrm{Zn}(\mathrm{OH})_{2}(\mathrm{s})+\mathrm{H}_{2} \mathrm{SO}_{4}(\mathrm{aq}) \rightarrow \mathrm{ZnSO}_{4}(\mathrm{aq})+2 \mathrm{H}_{2} \mathrm{O}(\ell)$ (c) $\mathrm{Ca}(\mathrm{s})+2 \mathrm{H}_{2} \mathrm{O}(\ell) \rightarrow \mathrm{Ca}(\mathrm{OH})_{2}(\mathrm{s})+\mathrm{H}_{2}(\mathrm{g})$

Which two of the following reactions are oxidationreduction reactions? Explain your answer in each case. Classify the remaining reaction.
(a) $\mathrm{Zn}(\mathrm{s})+2 \mathrm{NO}_{3}^{-}(\mathrm{aq})+4 \mathrm{H}_{3} \mathrm{O}^{+}(\mathrm{aq}) \rightarrow$
$\mathrm{Zn}^{2+}(\mathrm{aq})+2 \mathrm{NO}_{2}(\mathrm{g})+6 \mathrm{H}_{2} \mathrm{O}(\ell)$
(b) $\mathrm{Zn}(\mathrm{OH})_{2}(\mathrm{s})+\mathrm{H}_{2} \mathrm{SO}_{4}(\mathrm{aq}) \rightarrow \mathrm{ZnSO}_{4}(\mathrm{aq})+2 \mathrm{H}_{2} \mathrm{O}(\ell)$
(c) $\mathrm{Ca}(\mathrm{s})+2 \mathrm{H}_{2} \mathrm{O}(\ell) \rightarrow \mathrm{Ca}(\mathrm{OH})_{2}(\mathrm{s})+\mathrm{H}_{2}(\mathrm{g})$

Key Concepts

Oxidation States

Oxidation states provide a bookkeeping scheme to assign charges to atoms based on their electron configuration in compounds. By comparing the oxidation state of an element before and after a reaction, one can determine if electron transfer (oxidation or reduction) has occurred, which is fundamental for identifying redox reactions.

Oxidation-Reduction (Redox) Reactions

Redox reactions are chemical processes in which electrons are transferred from one species to another, changing the oxidation states of atoms involved. In these reactions, one substance is oxidized (loses electrons) while another is reduced (gains electrons). Identifying changes in oxidation numbers allows for the classification of a reaction as redox.

Reaction Classification

Reaction classification involves analyzing a chemical reaction to determine its type based on observed changes, such as shifts in oxidation states, formation of precipitates, or neutralization. When there is no change in oxidation states, the reaction may instead be classified as an acid-base or double displacement reaction.

Acid-Base Reactions

Acid-base reactions involve the transfer of protons between reactants, often leading to the formation of water and a salt. These reactions are typically characterized by the interaction of acids and bases rather than significant changes in oxidation states, distinguishing them from redox reactions.