Oxidation Numbers and Sulfate Ions

This video tutorial explains how to determine the oxidation numbers for each element in aluminum sulfate (Al2(SO4)3). It begins by discussing the neutrality of the compound and the rule that all oxidation numbers must sum to zero. The video then focuses on the sulfate ion (SO4) and its -2 charge, explaining how this affects the oxidation numbers of sulfur and oxygen. The tutorial proceeds to calculate the oxidation number of aluminum, showing that it must be +3 to balance the compound. Finally, the video demonstrates how to find the oxidation number of sulfur within the sulfate ion, concluding with a summary of the oxidation numbers for all elements in the compound.

What is the overall charge of aluminum sulfate?

• Variable

• Neutral

• Negative

• Positive

What is the charge of the sulfate ion (SO4)?

• 2-

• 0

• 1-

• 3-

How many sulfate ions are present in aluminum sulfate?

• 1

• 2

• 4

• 3

What is the oxidation number of aluminum in aluminum sulfate?

• +2

• +1

• +3

• +4

How is the oxidation number of sulfur in sulfate determined?

• By guessing

• By dividing the charge of the ion by the number of atoms

• By using the charge of the sulfate ion

• By assuming it is the same as oxygen

What is the oxidation number of sulfur in the sulfate ion?

• +5

• +6

• +7

• +4

How many oxygen atoms are in one sulfate ion?

• 5

• 2

• 3

• 4

What is the oxidation number of each oxygen atom in the sulfate ion?

• -1

• -2

• -3

• 0

What must the sum of oxidation numbers in a neutral compound equal?

• The atomic number

• The charge of the compound

• The number of atoms

• Zero

What is the purpose of calculating oxidation numbers in compounds?

• To find the compound's mass

• To predict chemical reactions

• To determine the compound's color

• To measure temperature