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Urgent help with chemistry...plsss!

[From: ] [author: ] [Date: 12-04-23] [Hit: ]
8. Al is the substance being reduced.pls say y i dont get which is which and y thank u so much!!!So an oxidizing agent is itself reduced and vice versa.......
Consider the following unbalanced equation.

Al(s) + Cu2+(aq) Al3+(aq) + Cu(s)

(a) Select all that apply.

1. Cu2+ is the substance being oxidized.
2. Al is the oxidzing agent.
3. Cu2+ is the substance being reduced.
4. Al is the substance being oxidized.
5. Al is the reducing agent.
6. Cu2+ is the reducing agent.
7. Cu2+ is the oxidizing agent
8. Al is the substance being reduced.

pls say y i dont get which is which and y thank u so much!!!

-
3 4 5 7
So an oxidizing agent is itself reduced and vice versa. Oxidation is loss of electrons so the state of the element would become more positive. If it is +1 lets say and it becomes +2 then it has been oxidized. The exact opposite applies for reduction.

-
Al + Cu2(aq) ----> Al3+(aq) + Cu

First you have to know the rules.
OILRIG. Oxidation Is Loss (of electron), Reduction Is Gain. This means if you start at a # (charge) and that number INCREASES, you've LOST electrons, because they are NEGATIVELY CHARGED.

e- (electron) = -1
Therefore if you gain electrons, you are ADDING A NEGATIVE charge.
-1 + -3 = -4 (= 4 electrons total). You've gained electrons. This is Reduction.
O + -2 = -2 = 2 electrons from zero. You've gained electrons.
2 + -2 = O = GAIN of electrons, because you've LOST a POSITIVE charge.
2+ + -1 = 1+, still a + charge, but GAINED an electron. Reduction.

p+ (proton) = +1
If you gain positive charge, you've LOST electrons, and this is Oxidation.
O + 3+ = +3p, therefore an addition of protons. Oxidation
-2 + 2+ = 0, addition of protons, oxidation

***All elementals in non-charged form have a ZERO oxidation number to start with.***
Therefore, in your stoichiometry, Al(s) and Cu(s) are ZERO.
Cu2+ has a charge of +2, and Al3+ has a charge of +3.

You have to go thru and do each math problem.
Al (0) ----> Al (3+)
0 + 3 = 3+... you gained positive charge.
You added protons. No negative charge was gained, so it had to be LOST.
Oxidation is LOSS.
Al is OXIDIZED.

Cu (2+) ----> Cu (0)
+2 + x = 0... don't you have to add a negative number to go from 2 to zero?
adding a negative number is GAINING electrons, because they are negative.
Reduction is GAIN.
Cu is REDUCED.

The reduced molecule gains its electrons from the oxidized molecule.
Therefore, that which is REDUCED, is the OXIDIZING AGENT.

The oxidized molecule loses its electrons to the reduced molecule.
Therefore, that which is OXIDIZED, is the REDUCING AGENT.

3, 4, 5, 7

Hope this helps to explain it! :)
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