Chemistry in Your Day : Bleached Blonde

Have you ever bleached your hair? Most home kits for hair bleaching contain hydrogen peroxide (H₂O₂), an excellent oxidizing agent. When applied to hair, hydrogen peroxide oxidizes melanin, the dark pigment that gives hair colour. Once melanin is oxidized, it no longer imparts a dark colour to hair, leaving the hair with the familiar bleached look. 


Hydrogen peroxide also oxidizes other components of hair. For example, protein molecules in hair contain - SH group called thiols. Hydrogen peroxide oxidizes these thiol groups to sulfonic acid groups (SO₃H). The oxidation of thiol groups to sulfonic acid groups causes changes in the proteins that compose hair, making the hair more brittle and easier to tangle. Consequently, people with heavily bleached hair must use conditioners, which contain compounds that form thin, lubricating coatings on individual hair shafts. These coatings prevent tangling and make hair softer and more manageable.


The following is a reaction of hydrogen peroxide with an alkene:


H₂O₂ + C₂H_{4 ->} C₂H₄O + H₂O


Taken from Chemistry: A Molecular Approach by Nivaldo J. Tro

Other Readings:

• Redox: Fundamentals, Processes and Applications
• Introduction to the High Temperature Oxidation of Metals
• Lab-Aids Introduction to Oxidation-Reduction Kit

Bone Density

As you may have heard, in today's society the issue of osteoporosis is really alarming especially to the seniors. Why is that? What is osteoporosis anyway? Let's talk about it!

Artificial hip joint

Comparison

Osteoporosis - which means porous bone - is a condition in which bone density becomes too low. The healthy bones of a young adult have a density of about 1.0 g/cm³. Patients suffering from osteoporosis, however, can have bone densities as low as 0.22 g/cm³. These low densities mean the bones have deteriorated and weakened, resulting in increased susceptibility to fractures, especially hip fractures. Patients suffering from osteoporosis can also experience height loss and disfiguration such as dowager’s hump, a condition in which the patient becomes hunched over because of compression of the vertebrae. Osteoporosis is most common in postmenopausal women, but it can also occur in people (including men) who have certain diseases, such as insulin-dependent diabetes, or who take certain medications, such as prednisone. Osteoporosis is usually tested by taking hip X-rays. Low-density bones absorb less of the X-rays than high-density bones, producing characteristic differences in the X-ray image that allow diagnostic. Treatments for osteoporosis include additional calcium and vitamin D, drugs that prevent bone weakening, exercise and strength training, and, in extreme cases, hip-replacement surgery.

Now you know what is osteoporosis and its bad effects, so better start drinking your milk!

Taken from Chemistry: A Molecular Approach by Nivaldo J. Tro

Other reading:

• The Myth of Osteoporosis by Gillian Sanson
• Osteoporosis: An Exercise Guide by Margie Bissinger
• Yoga for Osteoporosis: The Complete Guide by Loren Fishman

http://www.osteoporosis.ca/