TOPIC 3: Redox reactions Flashcards
What is a redox reaction?
A reaction where both oxidation and reduction occur.
What is oxidation?
The gain of oxygen or loss of electrons.
What is reduction?
The loss of oxygen or gain of electrons.
What is an oxidising agent?
Something that gets reduced (gains electrons or loses oxygen).
What is a reducing agent?
Something that gets oxidised (loses electrons or gains oxygen).
What is disproportionation?
It is when both oxidation and reduction have occurred on the same element
What does oxidation number relate to?
It relates to the charge on an element.
What are the rules for oxidation numbers?
- The oxidation number of any unclassified element is always 0.
- The sum of oxidation numbers will always be equal to the charge of the compound.
- The more electronegative element will always be negative.
- Fluorine will always be -1.
- The oxidation number of hydrogen is always +1 until it is with something less electronegative, then it will be -1.
- The oxidation number of oxygen is always -2 until it is in peroxide (two oxygens), and it is -1 in this case, or it is +1 with Fluorine.
How can you use oxidation numbers to recognize reactions?
You can use change in oxidation numbers to identify if a reaction is oxidised or reduced. If it increases in oxidation number then it is being oxidised and if it decreases in oxidation number then it is being reduced.
How do you balance half equations (simple method)?
Just balance the equation as you normally would.
How do you balance half equations (hard method)?
- Balance all non oxygen and hydrogen elements.
- Balance all oxygens using H2O.
- Balance all hydrogens using H+.
- Balance the oxidation numbers.
- Balance equations so changes are the same using electrons.
- Put both equations back together (excluding electrons).
