the reaction of aluminum metal (Al) with oxygen (O2) forms Al2O3. What is a balanced equation for this redox reaction. What are two half reactions to show how many electrons are gained or lost by each species?

Answer 1

Explain the effect of a decrease in pressure on the solubility of solute in a liquid solvent, gas and solid?

Answer 2

4Al + 3O2 ==> 2Al2O3

Al ==> Al^+3 + 3e
O2 + 4e ==> 2O^-2

Check my work.

Answer 3

The above response from DrBob222 is almost correct, but they forgot one important thing: we MUST maintain Conservation of Charge!

Aluminum is LOSING three electrons, while oxygen is GAINING four electrons, but Conservation of Charge tells us that we need to be gaining the same amount of electrons as we are losing.

Now that we've identified the number of electrons being lost is 3, and being gained is 4, we have our two numbers we can use to figure out the Least Common Multiple (LCM). The LCM of 3 and 4 is 12, so that is the amount of electrons that need to be lost and gained.

In order to achieve this, we multiply the aluminum half rxn by 4:
4(Al ==> Al^+3 + 3e-)

And we multiply the oxygen half rxn by 3:
3(O2 + 4e- ==> 2O^-2)

Our two new half reactions now look like this:
4Al ==> 4Al^+3 + 12e-
3O2 + 12e- ==> 6O^-2

These two half reactions properly show the losing and gaining of 12 electrons.