Which of the following are redox reactions? For those that are, indicate which element is oxidized and which is reduced. For those that are not, indicate whether they are precipitation or neutralization reactions. (a) $\mathrm{P}_{4}(s)+10 \mathrm{HClO}(a q)+6 \mathrm{H}_{2} \mathrm{O}(l) \longrightarrow$ (b) \(\mathrm{Br}_{2}(l)+2 \mathrm{~K}(s) \longrightarrow 2 \mathrm{KBr}(s)\) (c) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}(l)+3 \mathrm{O}_{2}(g) \longrightarrow 3 \mathrm{H}_{2} \mathrm{O}(l)+2 \mathrm{CO}_{2}(g)$ (d) $\mathrm{ZnCl}_{2}(a q)+2 \mathrm{NaOH}(a q) \longrightarrow \mathrm{Zn}(\mathrm{OH})_{2}(s)+$

Assign oxidation states for all elements in the reactants and products of the reactions. (a) \(\mathrm{P}_{4}(s)+10 \mathrm{HClO}(a q)+6 \mathrm{H}_{2} \mathrm{O}(l) \longrightarrow\) The oxidation states are as follows: \\ For P, the oxidation state is 0. \\ For H in HClO, the oxidation state is +1. \\ For Cl in HClO, the oxidation state is +1. \\ For H in H2O, the oxidation state is +1. \\ For O in H2O, the oxidation state is -2. (b) \(\mathrm{Br}_{2}(l)+2 \mathrm{K}(s) \longrightarrow 2 \mathrm{KBr}(s)\) \\ The oxidation states are as follows: \\ For Br in Br2, the oxidation state is 0. \\ For K, the oxidation state is 0. \\ For K in KBr, the oxidation state is +1. \\ For Br in KBr, the oxidation state is -1. (c) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}(l)+3 \mathrm{O}_{2}(g) \longrightarrow 3 \mathrm{H}_{2} \mathrm{O}(l)+2 \mathrm{CO}_{2}(g)\) \\ The oxidation states are as follows: \\ For C in CH3CH2OH, the oxidation state is -3. \\ For H in CH3CH2OH, the oxidation state is +1. \\ For O in CH3CH2OH, the oxidation state is -2. \\ For O in O2, the oxidation state is 0. \\ For H in H2O, the oxidation state is +1. \\ For O in H2O, the oxidation state is -2. \\ For C in CO2, the oxidation state is +4. \\ For O in CO2, the oxidation state is -2. (d) \(\mathrm{ZnCl}_{2}(a q)+2 \mathrm{NaOH}(a q) \longrightarrow \mathrm{Zn}(\mathrm{OH})_{2}(s)+\) \\ The oxidation states are as follows: \\ For Zn in ZnCl2, the oxidation state is +2. \\ For Cl in ZnCl2, the oxidation state is -1. \\ For Na in NaOH, the oxidation state is +1. \\ For O in NaOH, the oxidation state is -2. \\ For H in NaOH, the oxidation state is +1. \\ For Zn in Zn(OH)2, the oxidation state is +2.

Compare the oxidation states of the elements in the reactants and products to determine if there is a change in oxidation state. (a) The oxidation state of all elements involved remains the same. This reaction is not a redox reaction. (b) The oxidation state of Br changes from 0 to -1, and the oxidation state of K changes from 0 to +1. This reaction is a redox reaction. (c) The oxidation state of C changes from -3 to +4, and the oxidation state of O changes from 0 to -2. This reaction is a redox reaction. (d) The oxidation state of all elements involved remains the same. This reaction is not a redox reaction.

For redox reactions, identify which elements are oxidized (increase in oxidation state) and which are reduced (decrease in oxidation state). (b) In this redox reaction: \\ K is oxidized (going from 0 to +1). \\ Br is reduced (going from 0 to -1). (c) In this redox reaction: \\ C is oxidized (going from -3 to +4). \\ O is reduced (going from 0 to -2).

For reactions that are not redox reactions, determine if they are precipitation or neutralization reactions based on the products formed during the reaction. (a) This reaction involves an acid (HClO) and a base (H2O) and does not form a precipitate. It is a neutralization reaction. (d) This reaction involves an exchange of ions between the reactants to form a solid precipitate (Zn(OH)2). It is a precipitation reaction. In summary: (a) Neutralization reaction (b) Redox reaction: K is oxidized, and Br is reduced. (c) Redox reaction: C is oxidized, and O is reduced. (d) Precipitation reaction