[djrf12]

I had a few general chemistry questions that I was hoping someone could answer for me.

I understand that liquids oftentimes have cations and anions floating around in them. So for example water will have negatively charged hydroxyl and positively charged hydrogen floating around due to the disassociation of water and if you were to mix NaCl into the water then you would have positive and negatively charged Na and Cl ions too. Two questions. Are there any liquids that don't have any cations or anions mixed in with them, and if so what would be some examples of some nontoxic liquids with this property (and do they have a special name that distinguishes them)? And question two. I understand that pH meters are used to measure how many hydrogen ions are mixed in with an aqueous solution, but how would one go about experimentally measuring how many cations and anions are present in a given liquid solution? So for example lets say someone gave you a citric acid buffer of unknown pH that has some NaCl mixed in. You want to measure how many cations are present in the solution; how many H+ cations and how many Na+ cations. What instrument do you use to do this? My understanding is that a pH meter is only used to measure how many H+ cations there are, but wouldn't tell you how many Na+ cations are present in the liquid or any other types of cations that may be present. Is this right?

[Arkcon]

I had a few general chemistry questions that I was hoping someone could answer for me.

I understand that liquids oftentimes have cations and anions floating around in them. So for example water will have negatively charged hydroxyl and positively charged hydrogen floating around due to the disassociation of water and if you were to mix NaCl into the water then you would have positive and negatively charged Na and Cl ions too.

OK, that is a concise and clear statement of the facts.  Good job.

Two questions. Are there any liquids that don't have any cations or anions mixed in with them, and if so what would be some examples of some nontoxic liquids with this property (and do they have a special name that distinguishes them)?

Some liquids are non-ionic, and don't dissociate into ions.  Such materials have all covalent bonds, and no ionic bonds.  You can look those terms up to learn more.  Toxicity is a hard thing to define, but organic compounds don't ionize. 

And question two. I understand that pH meters are used to measure how many hydrogen ions are mixed in with an aqueous solution, but how would one go about experimentally measuring how many cations and anions are present in a given liquid solution?

A conductivity meter.

So for example lets say someone gave you a citric acid buffer of unknown pH that has some NaCl mixed in. You want to measure how many cations are present in the solution; how many H+ cations and how many Na+ cations. What instrument do you use to do this? My understanding is that a pH meter is only used to measure how many H+ cations there are, but wouldn't tell you how many Na+ cations are present in the liquid or any other types of cations that may be present. Is this right?

Well, if you had a pH meter,and you had a conductivity meter, can you see how you'd solve this problem?

*[EDIT: fixed failed quote]*

[djrf12]

OH, some liquids are non-ionic, and don't dissociate into ions.  Such materials have all covalent bonds, and no ionic bonds.  You can look those terms up to learn more.  Toxicity is a hard thing to define, but organic compounds don't ionize.

Great thanks for your help. This answers my question, but now I just thought of one more. Acetone and ethanol apparently have covalent bonds so I assume these would be examples of liquids that don't dissociate into ions, but lets say you were to take for example some acetone and dissolve in some NaCl. Since the NaCl has ionic bonds would it disassociate into Na and Cl ions? Or would only a covalently bonded solid not disassociate into ions if mixed in? Also, what would be an example of a covalently bonded solid that would dissolve in acetone?

Also, what about impurities? Wouldn't something like acetone have alot of impurities do to it being a good solvent and so have a lot of ions mixed in?

[Enthalpy]

Ethanol is a less than perfect example because it does dissociate a little bit. Less so than water, but enough to be a bad insulator, alas. It's just that ohmmeters and ammeters are so sensitive that they detect minute amounts of ions - and some applications can't accept such amounts.

This is prior to any impurity. Ethanol and acetone are likely to contain water, at least traces, which will spoil the conductivity, as would salt.

For a good insulator, take an alkane. They don't dissociate, are water-repellent, and don't dissolve compound in ionic form (or are there exceptions here?) so their conductivity isn't spoiled by mere exposure to air humidity.

Indeed, paraffins are used as "transformer oil" that resists higher fields than air does and better carries away the heat created by electric losses. They're essentially petroleum distillates very much refined to remove all S, N, P compounds as well as unsaturated hydrocarbons that would react with air over time.

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"Covalent bond" is never strict. Water has covalent bonds, but it does ionize a small little bit. 10^-7 would be damn little if we hadn't electric tools to observe it. One has to remove ions very much (ion exchange resins) to observe the conductivity of "pure" water.

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Covalent solid dissolved in acetone : many can, for instance polystyrene.