How do I balance this oxidation reaction equation?

Question

OK, it is aluminium reacting with nitrate ions in ALKALINE solution to give aluminate ions (AlO2)- and ammonia (NH3).

I can balance the aluminium oxidation in acid solution as Al + H2O ---> (AlO2)- + 2H+ but because it's alkaline I cant add H+ it has to be OH-. Can anyone help please? :)

Answer 1

I get:
8 Al + 3 NO3- + 5 OH- + 2 H20 -> 8 AlO2- + 3 NH3

I did this by putting variables before all ions and solving the five equations in 6 variables. (4 equations for the atoms and one for the charge)

Answer 2

It's a person I call KOHES!

K - KEY elements that react are written in your half equations
O - OXYGEN must be balanced on boths sides, if one side has more than you should add (H2O) to the other side to balance
H - HYDROGEN must be balanced on both sides, if theres more Hydrogen on one side.. add H+ *remember to cancel off the charges with (e-) electrons
E - ELECTRONS must be balanced.. the charges on the elements must be balanced on both sides. if not add electrons (minus) to balance it off
S - STATES should always be listed. E.g: (s), (aq), (l), (g)

Because this is Ammonia.. Nitrogen OR Hydrogen can REACT!
list the alkaline reaction for Hydrogen (as we know it is ampheprotic) - which is a reductant
Because Aluminium is too weak a oxidant and reductants can't react with each other. Oxygen is left to react!

Therefor the 2 half equations are:

O2 (g) + 2 H2O (l) + 4e- => 4OH- (aq)
H2 (g) + 2OH- (aq) => 2 H2O(l) + 2e- (x2 to create full equation and to allow the electrons to equal and cancelled out!)

Overall equation:
O2 (g) + 2 H2 (g) => 2 H2O (l)

get it?

Answer 3

8Al + 3(NO3)- + 5(OH)- +2H2O --> 8(AlO2)- + 3NH3

Answer 4

sorry i was fail in chemistry