Redox Flashcards
In terms of oxygen define oxidation
Gaining oxygen
In terms of oxygen define reduction
Loss of oxygen
In terms of oxygen define an oxidising agent
Provides oxygen and is in itself reduced
In terms of oxygen define a reducing agent
Removes oxygen and is in itself oxidised
In terms of hydrogen define oxidation
Loss of hydrogen
In terms of hydrogen define reduction
Gain of hydrogen
In terms of hydrogen define an oxidising agent
Removes hydrogen and is in itself reduced
In terms of hydrogen define a reducing agent
Gains hydrogen and is in itself oxidised
In terms of electrons define oxidation
Loss of electrons
In terms of electrons define reduction
Gain of electrons
In terms of electrons define an oxidising agent
Gains electrons and is in itself reduced
In terms of electrons define a reducing agent
Loss of electrons and is in itself oxidised
What is the oxidation number of an uncombined element or one combined with itself?
Always zero
What is the oxidation number of a simple ion (with only 1 element)?
Equal to its charge
What is the oxidation number of all group 1 elements?
Always +1
What is the oxidation number of all group 2 elements?
Always +2
What is the oxidation number of hydrogen?
+1, except in metal hydrides of group 1 and 2 wher e it becomes -1
What is the oxidation number of oxygen?
-2, except in peroxides (e.g. H2O2) where it becomes -1, and oxygen fluoride where it becomes +2
What is the oxidation number of fluorine?
Always -1
What is the oxidation number of chlorine?
Usually -1 (like in metal chlorides), but it changes when other non-metals are present
What is the oxidation number of a compound ion?
The sum of the oxidation numbers is equal to the charge on the ion
What is the definition of oxidation number?
The charge that a species would have if it was a simple ion
What is a disproportionation reaction?
The simultaneous oxidation and reduction of an element in a single species
Points for writing half equations
- reactions on the left and products on the right
- state symbols are usually included
- for an oxidation reaction, electrons can be shown on the left or the right
- for a reduction reaction, electrons are shown on the left
- the reaction must balance for charge
Writing a half equation for reduction (under acidic conditions)
After putting in the correct number of electrons gained, add H+ on the left and water on the right, then balance
Writing a half equation for oxidation (under alkaline conditions)
After putting in the correct number of electrons lost, add OH- on the left hand side and H2O on the right, then balance the charge by adding extra OH- ions
Combining half equations using the ion-electron method
Multiply one or both of the half equations so that the number of electrons lost or gained becomes the same in both equations, then add the two together to get the overall equation
Combining half equations using the oxidation number method
number of atoms of A x change in oxidation number of A = number of atoms of B x change in oxidation number of B
