Basic Changes of State, and Gases Question

[rubrboots]

Hello

I am currently working on a review before starting a senoir highschool chemistry course. I am now reviewing how to balance equations, which I do understand. But I dont understand how to determine the resulting state of the compound.
For example:

S8(s) + O2(g) ----------> SO2(g)

How do you know that the S (a solid) when combined with 02 (a gas) becomes a gas???

OR

Hg(l) + O2(g) ---------------> HgO(s)

liquid and a gas becomes a solid?

I am also wondering why oxygen is O , but the gas is 02. Same with Ammonium (NH4), but the gas state is (NH3).

I would really appreciate a quick explanation of these concepts, or the names of theories/subjects I should be investigating. Thank you very much.

[chemistrygosu]

Originally Posted by rubrboots

S8(s) + O2(g) ----------> SO2(g)

How do you know that the S (a solid) when combined with 02 (a gas) becomes a gas???

OR

Hg(l) + O2(g) ---------------> HgO(s)

liquid and a gas becomes a solid?

I am also wondering why oxygen is O , but the gas is 02. Same with Ammonium (NH4), but the gas state is (NH3).

I would really appreciate a quick explanation of these concepts, or the names of theories/subjects I should be investigating. Thank you very much.

First one. Sulfer in it's elemental state is a solid and is correctly labeled as S8 you just have to memorize that. You also just have to memorize that O2 is a gas under normal conditions, so is SO2. Oxygen forms covalent oxides with nonmetals. Which is what sulfer is. The reason O2 combines with S8 to form SO2 is because Oxygen again shares it's electrons. A rule of thumb is that oygen when combining with a nonmetal will generally form either two single bonds or one double bond. This is because it needs to attain an octect configuration. Or 8 electrons in it's outermost shell. The only compound containing Sulfer and oxygen that safisfies those rules is S02. Mercury in it's standard state is liquid.

When it combines with oxygen it forms an insoluble compound. Mecury I oxide. Memorize those solubility rules and you will see why it is a solid.

O2 is one of the diatomic molecules. Yes it's symbol is O but exists as two under normal conditions. It is VERY difficult to get an oxygen atom by it'self without another oxygen bonded to it because it again needs that filled shell of 8 electrons. And NH4 is ammonium and NH3 is ammonia. They are not the same thing. NH4 is weak acid NH3 is a weak base. One is not the gas phase and one the liquid phase. I hope that helped.

[rubrboots]

chemistrygosu

Thank you very much for replying. It has really helped me.