What does solubility mean, anyway? It depends upon who you are, what solubility means to you. If you are one of the above mentioned chemistry nerds or pencil-necks, solubility has a more formal definition than it does for the rest of us. Although there is bound to be someone in the scholastic community that will quibble or nit-pick this definition, solubility can be defined as the quantity of a substance that can be dissolved in a solvent at a certain temperature. This yields a saturated solution. Of course as the bounds of science are pushed by research and advances in technology, definitions are changed to reflect new understandings. Solubility is surely fair game. We learned early and eagerly that osmosis is the passage of water through a semi-permeable membrane. But now they have gone and changed it, and say osmosis is the passage of water or other solvent through a semi-permeable membrane. Where is the stability? What about all the work we did to memorize that, and then they go and change it? Can solubility be next in line for a distressing change in definition?
There are rules governing this, and many tests are passed or failed according to the student's application, understanding, or rote memorization of these rules for solubility. Here is a presentation of the rules in summary. It will be neither flowing prose nor poetry by any means. Chemistry is generally fascinating to the masses only when in very dilute solution.
Compounds of the ammonium ion, and of alkali metal, are soluble. Nitrates and acetates are soluble. Chlorides, bromides and iodides are soluble, excepting only those of silver, lead and mercury. Sulphates are soluble, excepting those of silver, lead, mercury, barium, strontium and calcium. Carbonates, sulfites and phosphates are insoluble, excepting those of ammonium and alkali metal. Hydroxides are insoluble, excepting those of ammonium, barium and alkali metal. Sulfides are insoluble, excepting those of ammonium, alkali metal and alkali earth metal. Oxides are insoluble, excepting those of calcium, barium and alkali metal; the soluble oxides react with the water to form hydroxides.
Ok, for most of us, unless we are trying to pass a required science course or are venturing into chemistry as a career, no understanding of the above paragraph is required. It is enough for us to know that solubility refers to the ability of some substance to be dissolved into a solution with a solvent. It might not sound like something that is important to you, but it is so. You doubt? Read on. Only a few examples will be required to convince you that solubility is a matter of grave importance to you. Actually, and literally, it is. Grave, as in you would be dead if the solubility rules were suddenly repealed. The solubility of various substances in body fluids determines our levels of wellness or disease. The solubility of vitamins and minerals is critical to our nutrition. Think about it, and show some respect for the principles of solubility when you get a chance.
There is a famous phrase that may be drifting about your synapses right now, something about solutions, solubility, or, hmmm... a seven-percent solution. Was that it? Yes, it was the famous book, then movie, called: The Seven-Per-Cent Solution: Being a Reprint from the Reminiscences of John H. Watson, M.D. in which, when asked what he was putting in his arm, the famous Holmes replied thus: "It is cocaine," he said, "a seven-per-cent solution. Would you care to try it?"
Please do not try it. The consequences can be serious and long-lasting, even fatal.
On a lighter note, and both less expensive and completely legal are the T-shirts, coffee mugs, and other geek oriented objects displaying the famous Henry J. Tillman quote: If you're not part of the solution, you're part of the precipitate. This of course refers to solubility and insolubility, with that which will not dissolve being the precipitate. It is funny, if you are of that turn of mind.
Well, as to that question, refer to the grave importance of solubility, mentioned above. But if mere mortality and the possibility of the early onset of death does not concern you, perhaps health and comfort will. There is a brown bottle commonly found in our cupboards, under-sink areas, or medicine cabinets. I do not refer here to Granny's 100-Proof Celery Tonic or to Gramps' Snake Bite Remedy, but to the common drug-store item, labeled Hydrogen Peroxide Solution. This household miracle cure is made possible by the solubility of hydrogen peroxide in water. It can clean your cuts and scrapes, help you keep your teeth and gums healthy, or even bleach your hair, if you care to and can acquire the strong solution. But if death holds no fear for you, and health and beauty are of little importance as well, there remains one important application of the principles of solubility that is bound to appeal.
Now, if you were born in the South, you know the importance of sweet tea. Even if you were not blessed with Southern birth, you must have ventured into an enlightened barbeque joint at some time and been exposed to the sweet solution. Aficionados know and will be happy to educate the misinformed concerning the impossibility of adding sugar to unsweetened tea to produce sweet tea at the table. They may not know their chemistry, but they do know their tea. Remember back at the beginning of this wise and funny discussion of solubility, when we referred to the simple definition of solubility, and mentioned that there were extensions and possible exceptions? Of course you do. Well here we are. We, the people of the South, and appreciators of sweet tea everywhere, know that only by adding sugar to hot or at least warm tea can you produce the perfect potion. Why, or why not? Solubility that is the answer. Hot water holds more sugar than cold water. So when you add sugar to hot fresh tea, or make your tea with prepared simple syrup, you get more sweetness in your sweet tea.
Solubility is important. It's a matter of life and death, even. Solubility also promotes the health and beauty of the body. Solubility principles are important to the production of beverages both mundane and sublime. Solubility; it's the solution to life's perplexing chemistry. Sweet, isn't it?