Redox Flashcards
1
Q
definition of oxidation (4)
A
- gain of oxygen
- loss of hydrogen
- loss of electrons
- increase in OS
2
Q
definition of reduction (4)
A
- loss of oxygen
- gain in hydrogen
- gain in electrons
- decrease in OS
3
Q
rules of assigning OS – in order (4 main, 9 in total)
A
- OS of free elements is 0 (unbonded elements)
- fixed OS
- fluorine always -1 (halogens)
- grp I, II, III usually +1 +2 +3 (when form ionic)
- oxygen usually -2, unless peroxide. superoxide
- hydrogen +1 (with non-metal), -1 (metal)
- simple ion –> charge of ions
- sum of OS in compound is 0
- sum of polyatomic = charge of ion
4
Q
which takes priority when assigning OS, shells or proton number
A
shells (acts as blockage) then proton number
5
Q
Why there is OS for covalent bond (eg CO₂)?
A
covalent -> no ions
- 2 diff types of NM, shared valence electrons tend to shift
- more proton, less electron shell -> attract electrons more strongly, pull them closer, ‘gaining’ electrons, having ‘partial charge’
6
Q
how to see oxidation and reduction in chemical equation?
A
assign oxidation number / charge number
7
Q
peroxide and superoxide charge?
A
O₂ ²⁻, O₂⁻
8
Q
Practice!
Na₂S₄O6 -> S?
A
+2.5
9
Q
Practice!
PCl₃ -> Cl?
A
-1
10
Q
Practice!
PCl₅ -> Cl?
A
-1
11
Q
Practice!
MnSO₄ -> Mn?
A
+2
12
Q
Practice!
Fe₃(PO₄)₂ -> Fe?
A
+2
13
Q
Practice!
Fe₃O₄ -> Fe
A
+2 2/3 or +2.67 (fine as a fraction)
14
Q
range of OS grp I, II, III, IV, V, VI, VII
A
I +1 II +2 III +3 IV +4 to -4 V +5 to -3 VI +6 to -2 VII +7 to -1
15
Q
OA RA
definition
A
OA oxidises other reactants but itself reduced
RA reduces other reactants but itself oxidised
