How do I know the states of matter for equations?

[TheRat]

How do I know the state of molecular compounds? I know that they can be solid liquid or gas, but how do I know which? For example H and O are gases at SATP but as a molecular compund they are a liquid. Also for acids, my textbook says that acids are solids liquids or gases as pure substances but then it says they are aqueous. What am I missing?

 

Thanks

[TheRat]

Do I just have to look up the molecular compound and copy the state? And for acids how do I know if its aqueous or not? My textbook doesn't explain this in a way that I understand (or provide answers at the back grrr) and I don't have a teacher to ask. Please help!!!

[swansont]

It's going to depend on the context of the problem you are trying to solve.

[daniton]

the answer depends on at what condition you are wandering.State of something is not something unique,only unique if you have standard conditions to determine and to compare with other things.

if possible make your question clear.

[TheRat]

I mean at SATP. I'm not so much asking in order to solve specific problems but more to know the 'rules' around this.

So specifically:

In what circumstances is an acid aqueous?

What are the rules determining the state of a molecular compound at SATP. Or are there no general rules?

 

I hope that makes sense!

[Genecks]

I think in the realm of chemistry, you'll often be considering things at room temperature and pressure (standard ambient temperature and pressure: SATP). If there are different conditions, more than likely you will be told the conditions. As such, in a course where memorization of the state of particular chemicals is important, there will be hints by the lecturer (most likely) in reference to the different states of particular chemicals at their varying temperatures and pressure whereby their associated states exist.

 

The noble gases are gases at room temperature.. Nitrogen can be liquid at a low temperature or high pressure, which I believe tends to be common for gases, as a high pressure or low temperature slows down the volatility and reduces the kinetic energy of the molecules.

 

CO₂ can be a gas or solid, which I guess depends on the energy that has been put into it, but as it has a gas form, it can be turned into a liquid, which if you've ever shot a paintball gun and loaded it with the right materials, you would know it it uses CO2 cartridges (for propellant), and thus things are put under high pressure (they have a thick metal casing), which allows the CO₂ to be a liquid... only when a person shoots the paintball gun does the liquid turn into a gas, thus allowing the energy (force from the gas) to be transferred to the paintball, so that it shoots out.

 

Hairspray is a similar example, which uses various organic compounds under pressure. CFCs were a big problem, so people stopped using those in hair spray.

 

 

Elemental gallium, if I remember correctly, is a metal that is solid at room temperature. However, it can melt in your hand at room temperature, given that heat rises from your hand. I had an interest in high school at my alternative high school for dropouts to buy galium metal or possibly stocks/shares/something in the metal, as I believed it would raise in price from the early 2000s onward, because it's used in computer equipment.

 

So, there are some SATP aspects to elements to remember and recall. Water and CO2 tend to be general examples of compounds to know. Hydrogen chloride is a gas, but when it is bubbled into a solution of H2O, it becomes dilute... If I remember correctly, this is due to water solvation (water shells) forming around the ions and cations dissociated from HCl. Nonetheless, if you've ever worked with HCl solutions, then you know the gas can come out of the aqueous solution over time, thus being toxic.

 

An acid that is aqueous means that it, the chemical itself (such as pure HCl), has dissociated (been placed in and broken apart by molecular forces into ions and cations) in a solution, such as H₂O.

 

http://en.wikipedia.org/wiki/Solvation

 

For a more dangerous example, VX nerve gas is ACTUALLY a liquid, but it has an evaporation rate whereby molecular forces and energy make the VX nerve agent molecules move apart from each other, whereby it becomes a gas. Similar to how water evaporates off a surface.

 

Then of course, you get into boiling point.. and that has to do with temperature and pressure...

 

It could be that your book sucks. If your book does suck and gives few examples, I suggest you start spending time with your instructor. First-year chemistry is not incredibly difficult, but there is a conceptual and imaginative quality to it.

 

I reason there are rules and a physics to understand the state of matter of various chemicals and elements, but that would be a whole science onto itself. In general, it has to do with energy, molecular forces, pressure, and temperature.

 

In a tough-as-nails course, you'll more than likely have to memorize the state of various chemicals and elements based on the problems, conditions of the chemical interaction, and whatever aspects occur in lecture in reference to the SATP. Yes, there is a level of memorization involved until you get into the physics of such things, whereby doing the physics requires much more ridiculous amounts of time.

 

Think "kinetics."

Also keep in mind the "conditions" of the experiment... and by experiment, I mean the chemical equations.

The conditions of importance would be temperature and pressure.

 

http://en.wikipedia.org/wiki/Necessary_and_sufficient_condition

http://en.wikipedia.org/wiki/Logical_conditional

 

Anyone feel free to correct me if I'm wrong, as my chem knowledge is rusty.

 

As this is more of a chemistry question than a homework question...

 

 

REQUEST FOR THREAD TO BE MOVED TO CHEMISTRY SUBBOARDS.

Edited March 29, 2013 by Genecks

[TheRat]

That's what I needed to know. Thanks!

[Genecks]

No problem.

 

I've dealt with the situation before, and I believe it's been asked here before, too.

 

Also, acids have varying states of matter. Make sure you re-read my stuff, because I edit often; but I'm done with the prior post.

Edited March 29, 2013 by Genecks