http://www.xing.com/net/chemgr/ Latest posts in XING group "Chemistry Corner (and not only)" en-en Copyright XING AG 08 Jan 2013 20:20:03 GMT Tue, 08 Jan 2013 20:20:03 -0000 en-support@xing.com en-support@xing.com epublica http://www.xing.com/img/xing/xing_logo_small.gif http://www.xing.com/net/chemgr/ 90 45 http://www.xing.com/app/forum?op=showarticles&id=43042687&articleid=43098007#43098007 &quot;Clever images&quot; about chemistry in our daily life http://www.chemistryviews.org/details/ezine/4007741/Shampoo_Science.html http://www.chemistryviews.org/details/ezine/1393243/What_Makes_a_Candle_Flame.html Fabio Terzi <en-support@xing.com> http://www.xing.com/app/forum?op=showarticles&id=43042687&articleid=43098007#43098007 Tue, 08 Jan 2013 20:10:48 GMT http://www.xing.com/app/forum?op=showarticles&id=43042687&articleid=43042765#43042765 The octanes of gasoline When you go to the gas station, you choose gasoline of 92 octanes, or 89, or 87... What do those octanes mean? The octane rating is a way to measure the gasoline's resistance to knocking. The knocking is a rapid pinging or knocking sound which comes from an engine when it's pushed to produce a lot of power quickly. Usually occurs when a car is accelerating, especially while going uphill. Gasoline is a blend of more than a hundred hydrocarbons (compounds with only carbon-h ... Roman Kurganov <en-support@xing.com> http://www.xing.com/app/forum?op=showarticles&id=43042687&articleid=43042765#43042765 Tue, 01 Jan 2013 10:34:13 GMT http://www.xing.com/app/forum?op=showarticles&id=43042687&articleid=43042762#43042762 Diesel fuels and the future Let's talk now about the diesel carburants. There are two main types of diesel, depending on its source: - Petrodiesel: a hydrocarbon mixture obtained in the fractional distillation of crude oil between 250 °C and 350 °C. Diesel is generally simpler to refine than gasoline and often costs less. It contains approximately 18% more energy per unit of volume than gasoline, which along with the greater efficiency of diesel engines contributes to fuel economy (distance ... Roman Kurganov <en-support@xing.com> http://www.xing.com/app/forum?op=showarticles&id=43042687&articleid=43042762#43042762 Tue, 01 Jan 2013 10:33:42 GMT http://www.xing.com/app/forum?op=showarticles&id=43042687&articleid=43042761#43042761 About commercial milk Many types of milk are sold in the market nowadays: homogenized, pasteurized... Here you can understand what all those names mean. - Homogenized: Milk is an emulsion which contains droplets of fat dispersed in a mixture of water, sugars and proteins. In the homogenization process the milk is forced through tiny tubes under pressure, so fat particles are broken up and dispersed evenly. Then the cream will not separate out upon standing. Here you can find more information. - ... Roman Kurganov <en-support@xing.com> http://www.xing.com/app/forum?op=showarticles&id=43042687&articleid=43042761#43042761 Tue, 01 Jan 2013 10:32:59 GMT http://www.xing.com/app/forum?op=showarticles&id=43042687&articleid=43042759#43042759 How is coffee decaffeinated? There are different ways of removing caffeine from coffee: - Water extraction: At the beginning solvents like dichloromethane or ethyl acetate were used because they dissolve selectively the caffeine. But because of their toxicity nowadays water is used instead. Hot water extracts both flavor ingredients and caffeine from green coffee beans. Then the extract is passed through activated charcoal and most of the caffeine is removed. Finally, soaking the original beans ... Roman Kurganov <en-support@xing.com> http://www.xing.com/app/forum?op=showarticles&id=43042687&articleid=43042759#43042759 Tue, 01 Jan 2013 10:32:05 GMT http://www.xing.com/app/forum?op=showarticles&id=43042687&articleid=43042754#43042754 Why do onions make you cry? Inside the onion cells there are some chemical compounds which contain sulfur. When you cut an onion, the cells break and those compounds suffer a chemical reaction and they are transformed into a more volatile sulfured compunds, which are released into the air. These sulfured compounds react with the moisture in your eyes forming sulfuric acid, which produces a burning sensation. The nerve endings in your eyes are very sensitive and so they pick up on this ... Roman Kurganov <en-support@xing.com> http://www.xing.com/app/forum?op=showarticles&id=43042687&articleid=43042754#43042754 Tue, 01 Jan 2013 10:30:37 GMT http://www.xing.com/app/forum?op=showarticles&id=43042687&articleid=43042750#43042750 Intolerance to lactose Lactose is the principal carbohydrate of milk. It's a pretty big compound (named disaccharide) formed by two smaller components: glucose and galactose. Such a big compound as lactose cannot get through the intestinal wall and into the bloodstream, so we need &quot;something&quot; to break it into smaller pieces. This &quot;something&quot; is an enzyme named lactase. The more milk and milk products we consume, the more lactase we need. Normally there's plenty of lactase in the digestive ... Roman Kurganov <en-support@xing.com> http://www.xing.com/app/forum?op=showarticles&id=43042687&articleid=43042750#43042750 Tue, 01 Jan 2013 10:29:37 GMT http://www.xing.com/app/forum?op=showarticles&id=43042687&articleid=43042748#43042748 How soap cleans? There are substances which can be dissolved in water, as for example the salt, and others which can't, as for example oil. Water and oil don't mix together, so if we try to clean an oily stain from a cloth or from the skin, water is not enough. We need soap. Soap is formed by molecules with a &quot;head&quot; which likes water (hydrophilic) and a long chain that hates it (hydrophobic). http://s19.postimage.org/3qeofhpgz/soap_molecule.gif1 Then when soap is added to the water, the long ... Roman Kurganov <en-support@xing.com> http://www.xing.com/app/forum?op=showarticles&id=43042687&articleid=43042748#43042748 Tue, 01 Jan 2013 10:28:46 GMT http://www.xing.com/app/forum?op=showarticles&id=43042687&articleid=43042742#43042742 Vegetables and colours An object is coloured because of the light that it reflects. White light from the sun contains all the wavelengths, but when it impacts on an object some of its wavelenghts are absorbed and some reflected. When we see an object of a certain colour, it's because it's reflecting more of that particular wavelength. For example red objects reflect 'red' light, which is light with a long wavelength. Many vegetables and fruits are strongly coloured because they contain an ... Roman Kurganov <en-support@xing.com> http://www.xing.com/app/forum?op=showarticles&id=43042687&articleid=43042742#43042742 Tue, 01 Jan 2013 10:26:31 GMT http://www.xing.com/app/forum?op=showarticles&id=43042687&articleid=43042732#43042732 The chemistry of love Do you think that there is real chemistry behind love? Yes! Chemistry is at the bottom of every step in a relationship, and this field is under continuous research. When you fall in love, your brain suffers some changes and also certain chemical compounds are released. Researchs usually consider three stages in love: lust, attraction and attachment. 1) Lust Lust is driven by initial physical attraction and flirting. This stage can depend on characteristics such as a ... Roman Kurganov <en-support@xing.com> http://www.xing.com/app/forum?op=showarticles&id=43042687&articleid=43042732#43042732 Tue, 01 Jan 2013 10:21:42 GMT