Oxidation State Worksheet
Grade 9 Chemistry worksheet focusing on understanding and calculating oxidation states for various elements and compounds.
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Oxidation State Worksheet
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Read each question carefully and provide your answers in the spaces provided. Show all your work for calculations.
Oxidation State (or oxidation number) is a number assigned to an element in a compound that represents the number of electrons lost or gained by an atom of that element in the compound. It helps us understand how electrons are distributed in a compound and is crucial for balancing redox reactions.
Rules for Assigning Oxidation States:
1. The oxidation state of an uncombined element is 0.
2. The oxidation state of a monatomic ion is equal to its charge.
3. In most compounds, oxygen has an oxidation state of -2 (exceptions: peroxides where it's -1, and with fluorine where it's +2).
4. In most compounds, hydrogen has an oxidation state of +1 (exception: metal hydrides where it's -1).
5. The sum of the oxidation states in a neutral compound is 0. The sum of the oxidation states in a polyatomic ion is equal to the charge of the ion.
1. What is the oxidation state of an uncombined element?
+1
-1
0
Varies
2. What is the usual oxidation state of oxygen in most compounds?
+1
-1
+2
-2
3. The sum of the oxidation states in a neutral compound is .
4. In metal hydrides, hydrogen has an oxidation state of .
5. Oxidation state helps us understand how are distributed in a compound.
6. Calculate the oxidation state of sulfur (S) in H₂SO₄.
7. Determine the oxidation state of chromium (Cr) in Cr₂O₇²⁻.
8. Find the oxidation state of nitrogen (N) in HNO₃.
9. The oxidation state of a monatomic ion is always 0.
True
False
10. In the compound OF₂, oxygen has an oxidation state of -2.
True
False
11. Explain why understanding oxidation states is important in chemistry, particularly when dealing with redox reactions. Provide an example.