Chlorine Chemistry

October 2006

Introduction: National Chemistry Week

The American Chemical Society, the biggest organization of professional chemists in the world, celebrates National Chemistry Week every October with programs and events to communicate the importance of chemistry to our quality of life. This year's theme, "Your Home - It's All Built on Chemistry," explores the many ways in which chemistry contributes to "Home Sweet Home."

Because chlorine chemistry plays such an important role in providing functional, safe and comfortable homes, this month's article features not just one compound, but several chlorine compound superstars.

Delivering Safe Water Safely

No More Small Beer

In Colonial North America, long before the era of municipal water treatment, families drank a weak alcoholic beverage called "small beer." This drink provided a source of fluid without putting family members at risk for waterborne sickness. The alcohol in small beer destroyed disease-causing germs that live in stream water, for example. Today, thanks to the use of chlorine disinfectants, water is disinfected before it enters your home, and you can drink tap water with a high degree of confidence that you will not become sick.

Clean tap water for drinking, cooking and bathing is essential to our day-to-day existence, and chlorine disinfectants, such as elemental chorine, sodium hypochlorite and calcium hypochlorite, used to purify water supplies, are essential to our health. In fact, almost all U.S. water systems that disinfect their water use some type of chlorine-based process to do so.

Increasingly, clean water enters homes and wastewater flows out through polyvinyl chloride, or PVC, pipes--products of chlorine chemistry. In many homes, PVC pipes have replaced traditional metal pipes. PVC pipes have the advantage of being inert, meaning that they do not react chemically with the water that flows through them or with the soil in which they may be buried. That helps ensure the quality of water remains high as it journeys from the treatment plant to the tap. Being inert also means PVC pipes last longer than metal pipes. And PVC pipes are much lighter than metal pipes, requiring less energy to transport to construction sites.

Controlling the Indoor Climate

Warm and cozy in winter, cool and comfy in summer-that's how we like our living spaces, and the products of chlorine chemistry help us become the masters of our indoor climates. For example, chlorine chemistry is used to produce the chemical building blocks needed to manufacture polyurethane foam wall and roof insulation. Insulation acts as a barrier to outside temperatures, reducing our fossil fuel use and household energy costs. Polyvinyl chloride windows and siding are also energy-efficient, long-lasting and save trees. PVC is recyclable too. According to the Vinyl Institute, one billion pounds (1,000,000,000 lbs.) of vinyl is recycled annually. 

Sanitizing Surfaces

Microscopic critters that live on raw meats or contaminated vegetables can wreak havoc in our homes by infecting family members and making them sick. Chlorine disinfectants are used to help destroy food-borne germs on kitchen preparation surfaces. Cutting boards, countertops and other food-contact surfaces can be disinfected with dilute chlorine bleach solutions, reducing the risk to the family of food-borne illness.

Chlorine disinfectants are used to sanitize the bathroom too. And a dilute solution of chlorine bleach (sodium hypochlorite) is handy for wiping down household surfaces when a family member is sick with a contagious "bug," such as a cold or flu virus. 

Indispensable to Hi-Tech Gadgets

It is hard to imagine a home today without hi-tech equipment. Most of our "gadgets" rely on computer technology, the brains of which are tiny silicon microprocessor chips that are produced using chlorine chemistry.

On a typical weekday morning you might rely on silicon microchips to help wake you up (alarm clock), heat up your muffin (microwave oven), check your e-mail (computer), and play music (CD player/MP-3 player) or watch the morning news (television). All that, before you even head out the door!

Follow-up Activities:

1. Based on the information in Chlorine Compound of the Month articles, compile a list of ten daily activities that depend on chlorine chemistry.
   
   
2. Visit National Chemistry Week student/educator resources for articles, activities and contests.
   
   
3. Visit the American Chemical Society's virtual chemistry club for high school students, called VC₂, and choose from a menu of activities that include molecular origami, chemistry mysteries and planning a science fair project.
   
   
4. Visit the Solutions through Science website and tour a virtual house and hospital to view more of the products of chlorine chemistry.

For a list of previous "Chlorine Compound of the Month" features, click here.