How Does Bleach Bleach? What Removes the Color?

Chemistry
When doing the laundry, we ask, what temperature should the water be, how much detergent should I use, will I need fabric softener, will I need bleach? If I use bleach, should I use chlorine bleach or should I use oxygen bleach? Kinds of Bleach There are two kinds of bleach, based on needed strength and fabric sensitivity. Chlorine bleach, historically the older and stronger variety, is based on sodium or calcium hypochlorite, NaOCl or CaOCl. One name brand of laundry bleach is Clorox®. It contains 5.25% NaOCl. How does chlorine bleach remove color? In order to understand that, we need first to ask, what is the chemistry behind the colors used in fabrics? Color in Fabrics When we think of colors applied to fabrics, the chemist usually thinks of…
Read More

Do Double Bonds Flip? Does Electron Density Move?

Chemistry
[caption id="attachment_7788" align="alignright" width="440"] 1,3,5 Hexatriene - NIST Image[/caption] How do double bonds flip, and what is the significance? The shorthand drawing of a double bond looks like an equal sign between two atoms. The double bond between the two carbon atoms of ethene gas, H₂C=CH₂, well illustrates this. Some organic compounds possess conjugated (alternating) double bonds. A simple example of this is 1,3,5-hexatriene. [caption id="attachment_7785" align="alignright" width="340"] Fig. 1. 1,3,5 Cyclohexatriene.[/caption] What If? But what if the ends of that 1,3,5 hexatriene are joined, with the loss of two hydrogen atoms, to make a ring one might be tempted to call 1,3,5-cyclohexatriene? In fact, such a molecule, if flipped left-to-right, is seen to be identical with 2,4,6-cyclohexatriene! The numbers can be dropped and the molecule can simply be named…
Read More

The Quintessential Aromatic Hydrocarbon Benzene (Pt.1)

Chemistry
[caption id="attachment_14959" align="alignright" width="440"] Cyclohexane - Chair Form[/caption] Benzene? What's that? Living creatures universally share an important characteristic: they all are constructed of carbon-containing compounds. For that reason, chemists call such compounds organic. Now the term organic has taken on additional meaning. Compounds that are similar, but not found in nature, are also called organic compounds. One group of organic compounds, whether found in nature or not, possess special properties—chemical and physical—that put them into a category apart. Once it was thought such compounds were distinguishable by smell or aroma. Each was labeled an aromatic, and—the property itself—aromaticity. Simple Hydrocarbons The simplest hydrocarbon1 is methane (CH4)—a gas. It possesses a tetrahedral structure, with a carbon atom at its center and four hydrogen atoms at the corners (See Figure 1). Since…
Read More