(U1) Redox Flashcards
What is redox?
Oxidation and reduction occur simultaneously in the same reaction
Redox reactions involve the transfer of electrons between two species.
Define oxidation.
Loss of electrons / Increase in oxidation state
Oxidation can also involve the addition of oxygen or removal of hydrogen.
Define reduction.
Gain of electrons / Decrease in oxidation state
Reduction can also involve the addition of hydrogen or removal of oxygen.
What is an oxidising agent?
Electron acceptor
The oxidising agent is reduced in the process of oxidation.
What is a reducing agent?
Electron donor / provider
The reducing agent is oxidized in the process of reduction.
What is disproportionation? (3)
- Oxidation and reduction
- of the same element
- in the same reaction
Disproportionation reactions are a form of Redox reaction
When 2 electronegative elements are in the same compound, which one has a positive oxidisation number?
The less electronegative element
E.g. F2O —> F=-1 | O=+2 (as fluorine is more electronegative)
What is the oxidation number of Oxygen generally?
What is it in a peroxide?
- usually -2
- -1 in H2O2
What is the oxidation number of hydrogen generally?
What is it in a metal hydride?
- usually +1
- -1 in metal hydrides e.g. NaH
What oxidation number do compounds add to?
0
When does the oxidation number of halides change from -1?
When bonding with more electronegative elements such as Oxygen or Fluorine
In NH3, why does the Nitrogen acquire a ∂- charge?
The nitrogen atom uses 3 electrons to form covalent bonds with hydrogen atoms
What is the O.N. of any ion?
It’s charge
When writing half equations, what can be added to each side?
- electrons
- H+ ions
- OH- ions
- H2
Remember, find which reduces and oxidises, then apply the rules:
reduction is:
- gain of electrons
- gain of hydrogen
- decrease in oxidation state
Oxidation is the opposite
