I'm so confused!
Al + O2 -> Al2O3
This is supposed to be a balanced equations but how did it go from 2 oxygens to 3?
Hi it’s me 12 years later
It's the FORMULA. Don't confuse balancing with writing a formula.
Aluminum is Al.
O2 is oxygen and it is almost always written as a diatomic molecule. Others, in their free state. written as diatomic molecules, are H2, O2, N2, F2, Cl2, Br2, I2 (and their cousins S8 and P4).
For aluminum oxide, the valence of Al is +3, the valence of oxygen is -2 (in most cases), so the formula for aluminum oxide is Al2O3.
Rule 1 in balancing equations is:
You may NOT change any subscript to balance an equation. You may change coefficients ONLY.
And no, the equation is not balanced. Why can I say that? Because we have 1 Al on the left and 2 on the right. Not balanced. We have 2 O on the left and 3 on the right. Not balanced. So how do we balance it.
First we look on the right and we see 2 Al on only 1 on the left; therefore, we place a 2 in front (as a coefficient) of Al. That balances Al (we will need to change that later). Then we look at the 3 O on the right and 2 O on the left and say how do we do that. There is no integer I can multiply either by to get the other. So we use something that will get a common multiple. For example, if I place a 2 as a coefficient for Al2O3, that will give me 6 O atoms on the right. That lets me place a 3 as a coefficient for O2 on the left to have 6 O atoms on the left. Having done all that to balance the oxygen atoms, I realize I messed up on Al, which I already had done. But not to worry. We can fix that. Having O done, we look and see we need 4 Al so we can change the 2 Al on the left to 4 Al. The final equation looks like this.
4Al + 3O2 ==> 2Al2O3. Now we check it.
4 Al on the left and 4 on the right.
6 O on the left and 6 on the right. All done. Let me know if there is anything you don't understand.
There are a few rules that govern many products. Some we just memorize but most are governed by sets of rules. For example, there are
synthesis reactions (the 4Al + 3O2 ==> 2Al2O3 is a synthesis reaction; i.e., we take two atoms and make a molecule.)
decomposition reactions. An example is
2HgO ==> 2Hg + O2 where one substance breaks down to form two or more substances. Actually, you will see this is just the reverse of the synthesis reaction.)
single replacement reactions.
2Al + 6HCl ==> 2AlCl3 + 3H2 where a single substance, usually a metal, replaces the H in a compound.
double displacement reactions.
AgNO3 + NaCl ==> AgCl + NaNO3 where the positive and negative ions simply change places. The Ag goes with the Cl and the Na goes with the NO3^-.
Acid + base gives a salt + water.
There are others but you will learn them as you. So we try to learn rules to write equations (essentially predicting products) to keep from memorizing thousands of reactions. You're right! There are thousands.
Thanks! I feel pretty stupid now..
I was also curious about predicting products. How on EARTH would you do that when there are so many products?
Ah, chemistry can be quite confusing, just like trying to understand a clown's logic. But fear not, my curious friend, I'll try my best to shed some humorous light on this!
You see, in the balanced equation Al + O2 -> Al2O3, it might initially seem like there's an oxygen rebellion going on, with 2 oxygens turning into 3. But, it's not really a rebellion, it's more of an oxygen expansion plan!
The key is to look at the elements individually. On the left side, we have 2 oxygens bonded together as O2, while on the right side, we have 3 oxygens forming Al2O3. In this reaction, Al2O3 is a compound made up of two aluminum atoms (Al) and three oxygen atoms (O).
So, even though it might seem like a numerical mystery, it's just a matter of combining elements to form a new compound. Think of it as the oxygens multiplying in this reaction, like they're planning for a little oxygen family expansion!
I hope that brings a smile to your face, and maybe even a little clarity to the equation conundrum. Just remember, chemistry can be a puzzling circus, but don't worry, the clowns are here to make you laugh along the way!
The balanced chemical equation you provided is:
2 Al + 3 O2 → 2 Al2O3
To understand how the equation is balanced, we need to look at the individual elements involved. In this case, we have aluminum (Al) and oxygen (O2).
First, let's start with aluminum. There are two atoms of aluminum on the left side of the equation (2 Al). To balance the aluminum atoms, we must have the same number of aluminum atoms on the right side. Therefore, we also have 2 Al on the right side.
Next, let's consider oxygen. On the left side, we have 3 molecules of oxygen (3 O2). To balance the oxygen atoms, we need to determine the number of molecules of Al2O3 required on the right side. Since each molecule of Al2O3 contains three oxygen atoms, we need 2 molecules of Al2O3 on the right side to have a total of 6 oxygen atoms (2 molecules × 3 oxygen atoms per molecule). Therefore, we have 2 Al2O3 on the right side.
Now, let's count the number of atoms on each side of the equation:
Left side: 2 Al + 3 O2
Aluminum atoms: 2
Oxygen atoms: 3 × 2 = 6
Right side: 2 Al2O3
Aluminum atoms: 2 × 2 = 4
Oxygen atoms: 2 Al2O3 × 3 oxygen atoms per molecule = 6
As you can see, the number of atoms of each element is now balanced on both sides of the equation. This is how the equation is properly balanced with 2 oxygens on the left side and 3 oxygens on the right side.