miércoles, 11 de abril de 2012

Why is Acetone soluble in water?

Acetone is polar and water is polar. the solubility rule is as follows: "like dissolve like" meaning the more similar the polarity of two substances, the greater their ability to interact with each other.The carbonyl (i.e. C=O)residue in acetone (CH3COCH3 is the real formula) which is polar in nature due to the difference in electronegativity b/wn C and O, forms an overall molecular dipole in acetone. This molecular dipole is nearly identical to water--in fact, acetone has a dielectric constant of about 77 while water's dielectric constant is about 80 at room temperature and thus would be soluble in water.

Hydrogen bonding DOES occur between acetone and water as the oxygen of acetone's cabonyl can hydrogen bond with the O-H bonds of water. However, the presence of such hydrogen bonding would in fact only lend to the ability of the two types of molecules to be miscible with each other.

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GREEN CHEMICALS

The Green Seal certification is granted by the organization with that name and has a great number of members contributing with the requirements to pass a raw material or a chemical product as "green". Generally for a material to be green, has to comply with a series of characteristics like: near neutral pH, low volatility, non combustible, non toxic to aquatic life, be biodegradable as measured by oxygen demand in accordance with the OECD definition.
Also the materials have to meet with toxicity and health requirements regarding inhalation, dermal and eye contact. There is also a specific list of materials that are prohibited or restricted from formulations, like ozone-depleting compounds and alkylphenol ethoxylates amongst others. Please go to http://www.greenseal.com/ for complete information on their requirements.
For information on current issues regarding green chemicals, see the blog from the Journalist Doris De Guzman, in the ICIS at: http://www.icis.com/blogs/green-chemicals/.
Certification is an important — and confusing — aspect of green cleaning. Third-party certification is available for products that meet standards set by Green Seal, EcoLogo, Energy Star, the Carpet & Rug Institute and others.
Manufacturers can also hire independent labs to determine whether a product is environmentally preferable and then place the manufacturer’s own eco-logo on the product; this is called self-certification. Finally, some manufacturers label a product with words like “sustainable,” “green,” or “earth friendly” without any third-party verification.
“The fact that there is not a single authoritative standard to go by adds to the confusion,” says Steven L. Mack M.Ed., director of buildings and grounds service for Ohio University, Athens, Ohio.
In www.happi.com of June 2008 edition, there is a report of Natural formulating markets that also emphasises the fact that registration of "green formulas" is very confused at present, due to lack of direction and unification of criteria and that some governmental instittion (in my opinion the EPA) should take part in this very important issue.