CHM
1032C Learning Tools
Oxidation - Reduction Reactions
CHM
1032C Learning Tools
Oxidation - Reduction Reactions
Example 1
Consider the reaction between aluminum and aqueous copper(II) sulfate:
____Al(s) + ____CuSO4(aq) ® ____Al2(SO4)3(aq) + ___Cu(s)
Balance the equation. Then answer the questions.
In this reaction, Al {lost/gained}{how many?1 2 3 4 5} electrons. Aluminum was {oxidized/reduced} and is the {oxidizer/reducer}. The copper in CuSO4 {lost/gained}{how many?1 2 3 4 5} electrons. The copper was {oxidized/reduced} and is the {oxidizer/reducer}. What type of reaction is this? What is the driving force of the reaction? Answer 1Example 2
Consider the reaction below:
____C4H10(g) + ___O2 ® ____CO2(g) + ___H2O(g)
Balance the equation. Then answer the questions.
In this reaction, each C in butane {lost/gained}{how many?1 2 3 4 5} oxygens. Carbon was {oxidized/reduced} and is the {oxidizer/reducer}. The O in O2 gas {lost/gained}{how many?1 2 3 4 5} electrons from each of the carbons. The oxygen was {oxidized/reduced} and is the {oxidizer/reducer}. What type of reaction is this? What is the driving force of the reaction? Answer 2Example 3
Consider the reaction below:
_____Sc(s) + ____H2SO4(aq) ® ____Sc2(SO4)3 + ____H2(g)
Balance the equation. Then answer the questions.
In this reaction, Sc {lost/gained}{how many?1 2 3 4 5} electrons. Scandium was {oxidized/reduced} and is the {oxidizer/reducer}. The H in H2SO4 {lost/gained}{how many?1 2 3 4 5} electrons. The hydrogen was {oxidized/reduced} and is the {oxidizer/reducer}. What type of reaction is this? What is the driving force of the reaction? Answer 3
Answer 1 2Al(s) + 3CuSO4(aq) ® Al2(SO4)3(aq) + 3Cu(s)
In this reaction, Al {lost}{3} electrons. Aluminum was {oxidized } and is the {reducer or reducing agent}. The copper in CuSO4 {gained}{2} electrons. The copper was { reduced} and is the {oxidizer or oxidizing agent}. Note that the total number of electrons transferred from Al to Cu is 6: 3 electrons from each of the 2 aluminums. There are 3 coppers gaining 2 electrons apiece. This reaction fits the single replacement pattern of chemical reactions. The driving force of all redox reactions is the transfer of electrons. In this case, it is the transfer of electrons from the more active metal, Al, to the less active metal ion, Cu2+.Answer 2 2C4H10(g) + 13O2 ® 8CO2(g) + 10H2O(g)
In this reaction, each C in butane {gained}{2} oxygens. Oxidation can be thought of as increasing in the number of oxygens, therefore: Carbon was {oxidized } and is the { reducer or reducing agent}. The O in O2 gas {gained}{2} electrons from each of the carbons. Remember, that the most electronegative element in a compound has a charge (or oxidation number) that is equal to the group number of the element minus 8. So oxygen in carbon dioxide is -2 while as O2 it is neutral. The oxygen was {reduced} and is the {oxidizer or oxidizing agent }. The reaction of hydrocarbons with oxygen is known as combustion, and the driving force is the transfer of electrons from the carbon to the oxygen.Answer 3 2Sc(s) + 3H2SO4(aq) ® Sc2(SO4)3 +3H2(g)
Balance the equation. Then answer the questions.
In this reaction, Sc {lost}{3} electrons. Remember that you can determine the charge of Sc by examining the formula of scandium(III) sulfate. The sulfate ion is -2 so scandium must be the +3 ion. Scandium was {oxidized} and is the {reducing agent}. The H in H2SO4 {gained}{1} electron. Remember that H is +1 when bonded to nonmetals, and neutral as an element. The hydrogen was {reduced} and is the {oxidizing agent}. The reaction is single replacement, and the driving force is the transfer of electrons from the more active Sc to the less active H.