High School Chemistry : Help with Single-Replacement Reactions
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Example Questions
Example Question #3 : Electrochemistry
Which of the following reactions involves both reduction and oxidation reactions?
Both single displacement reactions and the reaction of sodium chloride and calcium sulfate
Single displacement reactions
The reaction of sodium chloride and calcium sulfate
Neither single displacement reactions nor the reaction of sodium chloride and calcium sulfate
Single displacement reactions
A reaction that has both reduction and oxidation half reaction is called a redox reaction. It involves one or more atoms gaining electrons (reduction) and one or more atoms losing electrons (oxidation). Recall that single displacement reactions involve the replacement of an element in a compound with another element. An example of single replacement reaction is shown below:
In this reaction, a sodium atom replaces a calcium atom in calcium sulfate. If we calculate the oxidation numbers for sodium and calcium, we can see that sodium loses an electron (the oxidation state goes from 
Reaction of sodium chloride and calcium sulfate is as follows:
If we calculate the oxidation state of each atom we will notice that oxidation number doesn’t change; therefore, this isn’t a redox reaction.
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