Bilangan Oksidasi | Kimia kelas 10 | Kimia kelas 12

Summary

In this educational video, the presenter introduces the concept of oxidation states, focusing on their definitions and how to determine them. Key rules include the oxidation states of free elements, metals, hydrogen, fluorine, and oxygen, along with the importance of the total sum in compounds and ions. Practical examples, such as KMnO₄ and NaNO₃, illustrate how to calculate oxidation states using systematic methods. The video aims to simplify the understanding of redox reactions by breaking down complex concepts into digestible parts, making it a valuable resource for chemistry students.

Takeaways

• 😀 Oxidation numbers (oxidation states) represent the relative charge of an atom compared to others in a molecule or ion.
• 😀 Free elements have an oxidation number of zero, regardless of their atomic structure.
• 😀 Metals in compounds have oxidation numbers equal to their group numbers: Group 1A = +1, 2A = +2, 3A = +3.
• 😀 Hydrogen generally has an oxidation number of +1, but it can be -1 in metal hydrides.
• 😀 Oxygen typically has an oxidation number of -2, but it can be -1 in peroxides and +2 in certain compounds.
• 😀 The sum of oxidation numbers in a neutral compound equals zero, while in an ion, it equals the ion's charge.
• 😀 In the example KMnO4, the total oxidation state is zero, resulting in Mn having an oxidation number of +7.
• 😀 In MnO4^-, the total oxidation state is -1, also yielding an oxidation number of +7 for Mn.
• 😀 In NaNO3, sodium has an oxidation number of +1, nitrogen +5, and the overall sum is zero.
• 😀 In the ion C2O4^2-, the total oxidation state is -2, leading to each carbon atom having an oxidation number of +3.

Q & A

What is the definition of oxidation number?

Oxidation number is the relative charge of an atom compared to other atoms in a molecule or ion.

What is the oxidation number of a free element?

The oxidation number of a free element is always zero.

How do you determine the oxidation number of metals in compounds?

Metals in Groups 1A, 2A, and 3A have positive oxidation numbers equal to their group number; for example, Group 1A metals have +1, Group 2A metals have +2, and Group 3A metals have +3.

What is the common oxidation number of hydrogen in compounds?

Hydrogen generally has an oxidation number of +1, but it can be -1 in metal hydrides.

What is the usual oxidation number of oxygen in compounds?

Oxygen typically has an oxidation number of -2 in compounds, but it can be -1 in peroxides and +2 in oxyfluorides.

What is the significance of the total oxidation number in a neutral compound?

In a neutral compound, the total oxidation number must equal zero.

How do you determine the oxidation number of elements in ions?

In ions, the total oxidation number equals the charge of the ion.

In the compound KMnO₄, what is the oxidation number of manganese (Mn)?

In KMnO₄, the oxidation number of manganese (Mn) is +7.

What is the oxidation number of nitrogen (N) in the compound NaNO₃?

In NaNO₃, the oxidation number of nitrogen (N) is +5.

What is the oxidation number of carbon (C) in the oxalate ion (C₂O₄²⁻)?

In the oxalate ion (C₂O₄²⁻), the oxidation number of carbon (C) is +3.