Redox 1 Flashcards
What is oxidisation?
The loss of electrons
What is reduction?
The gain of electrons
What is oxidisation number?
a number which gives the oxidisation state of an element or ionic substance
State the 8 rules and the two rule exceptions to assigning oxidisation number
rules:
-The oxidisation number of an element is 0
-oxidisation numbers in a neutral compound add up to zero
-oxidisation numbers in a charged compound add up to the total charge
-hydrogen has an oxidisation number of +1
-oxygen has an oxidisation number of - 2
-halogens have oxidisation number of -1
-Group 1 metals have oxidation number +1
-Group 2 metals have the oxidisation number +2
exceptions:
oxygen has a oxidation number of -1 in peroxides
-hydrogen has an oxidisation number of -1 in metal hydrides
What are roman numerals used for?
Can tell you the oxidisation number of an element that has a variable oxidisation state.
In terms of oxidisation numbers what usually happens to the s-block elements in the periodic table?
lose electrons - so are oxidised - oxidation number increases
In terms of oxidisation numbers what usually happens to the p-block elements in the periodic table?
gain electrons - so are reduced - oxidation number decreases
What is an oxidising agent?
Accepts electrons from the species that is being oxidised so gains electrons and is reduced - oxidisation number will increase
What is a reducing agent?
donates electrons to the species that is being reduced so loses electrons and is oxidised - oxidisation number will decrease
What is a redox reaction?
Where there is both oxidisation and reduction in a reaction
What is a disproportionate reaction?
Where a species is both oxidised and reduced
What is the method of writing half equations?
- balance all species excluding hydrogen and oxygen
2.balance oxygen using h20
3.balence hydrogen using H+ ions
4.balance charges by using e-
