Redox Flashcards
What is the oxidation state of an uncombined element? Eg: Na
0
Define Reduction
A gain of electrons, where the donor atom is itself oxidised
What is always transferred in a redox reaction?
Electrons
What is the use of finding Oxidation states?
To see what has been oxidised and in turn what has been reduced in a reaction
What is the oxidation state of N in HNO3 ?
+5
What is the general oxidation state of Hydrogen, and when does this number change?
Usually +1, except in metal hydrides
What is the oxidation state of elements Lithium to Francium?
Always +1 (Group 1)
What is the general oxidation state of Oxygen, and when does this change?
Generally -2 except in a Peroxide or with Flourine
What is the oxidation state of S in H2SO4 ?
+6
Define oxidation
Gain of electrons where the donator itself is reduced
When is an equation balanced?
When the number of atoms of each element is the same either side & the total charge on each side is the same.
What is the oxidation state of P in PCl5?
+5
What has been Oxidised and what has been Reduced in this reaction?:
CuO+Mg–>MgO+Cu
Cu (Copper) has been reduced (+2e’s)
Mg (Magnesium) has been oxidised (-2e’s)
What is the oxidation state of S in SO4(2-) ?
+6
What is Oxygen in this reaction?
Fe2O3 + Al –> Fe + Al2O3
A spectator ion
How many electrons have been gained in this reaction.
MnO4(-) –> Mn(2+)
5 electrons gained
Manganese reduced from +7 to +2
Has Aluminium been oxidised or reduced in this equation?
Al –> Al(3+) + 3e-‘s
Oxidised
What is the oxidising and reducing agent in this reaction?
Ca + Br –> (Ca(2+) + 2Br-)
Oxidising agent: Ca
Reducing agent: Br
What is a half equation?
Two “halves” of the overall ionic equation for a redox reaction, used to show the oxidation and reduction of elements within the reaction
What 3 things can only be added to balance/complete a redox reaction?
H+ ions
Electrons
H2O
