Oxidation Numbers and Chromium Compounds

This video tutorial explains how to determine the oxidation number of chromium in chromium(III) oxide (Cr2O3). It begins by introducing the concept of oxidation numbers and the rule that the sum of oxidation numbers in a compound equals zero. The video then discusses the typical oxidation state of oxygen as -2 and how this applies to Cr2O3. Two methods are presented to calculate the oxidation number of chromium: one using direct calculation and another using algebraic equations. The video concludes by confirming the oxidation number of chromium as +3, explaining why Cr2O3 is called chromium(III) oxide.

What is the oxidation number of oxygen in most compounds?

• +1

• 0

• -2

• +2

In Cr2O3, what is the total oxidation number contributed by the oxygen atoms?

• -6

• +6

• -3

• 0

How many chromium atoms are present in the compound Cr2O3?

• 3

• 4

• 2

• 1

What is the oxidation number of chromium in Cr2O3?

• +2

• +3

• +4

• +6

Which method can be used to verify the oxidation number of chromium in Cr2O3?

• Using a periodic table

• Algebraic method

• Using a calculator

• Trial and error

What is the sum of oxidation numbers in a neutral compound like Cr2O3?

• -3

• +3

• 0

• +6

Why is Cr2O3 referred to as chromium(III) oxide?

• Because it is a trioxide

• Because it is the third compound of chromium

• Because chromium has an oxidation number of +3

• Because it contains three oxygen atoms