If you've ever poured hydrogen peroxide solution onto a cut and didn't experience the expected fizz, it's likely your bottle of hydrogen peroxide has become a bottle of plain water. The 3% hydrogen peroxide solution you can buy for use as a disinfectant typically has a shelf life of at least a year if the bottle is unopened, but only lasts 30-45 days once the seal has been broken. As soon as you expose the peroxide solution to air, it starts to react to form water. Also, if you contaminate the bottle (e.g., by dipping a swab or finger into the bottle), you can expect the effectiveness of the remaining liquid to be compromised.

So, if you have a bottle of hydrogen peroxide that has been sitting in your medicine cabinet for a few years, it would be a good idea to replace it. If you've opened the bottle at any point, its activity is long-gone. If you feel like testing the solution. Solvay Chemicals describes a test you can perform to assess the remaining activity.

February 9^th is the birthday of the United States Weather Bureau. Professor Lapham of Milwaukee was instrumental in raising awareness for a need for the government to pay attention to weather. He frequently forwarded clippings of newspaper articles outlining the deaths of sailors due to severe Great Lake storms. Congress passed the legislation and President Ulysses S. Grant established the Bureau in 1870. The official name for this agency was "The Division of Telegrams and Reports for the Benefit of Commerce". The agency granted the Secretary of War to maintain meteorological observations and data and to warn citizens of approaching storms. The task was assigned to the War Department because it was believed military discipline would allow the "greatest promptness, regularity, and accuracy" needed to maintain the service. Every day, personnel from the Signal Service Corps would report weather information to Washington DC.

The Weather Bureau would evolve over time to become the National Weather Service under the administration of the National Oceanic and Atmospheric Administration. Find out what else occurred on this day in science history.

Here's an extremely simple science project you can try. All you need is duct or duck tape. It doesn't matter which name you call it, but your results seem to depend partially on the brand you use: Henkel™ works well.

What You Do

Tear off two strips of tape. Stick the pieces together with the sticky sides facing each other, leaving enough tape so that you can pull the strips apart. Turn out the lights. Give your eyes a minute or two to adjust to the dark. Pull the strips of tape apart.

What Happened

Did you see the blue line where the tape separated? (NurdRage has a video if you'd like to see what to expect.) This is triboluminescence, which is a type of luminescence triggered by mechanical energy or electrical energy from an action such as friction. You can get the same effect from other types of tape as well. A good one to try is transparent Scotch™ tape.

My camera was not sufficiently sensitive to take a photo of this effect, but you may be able to capture tape triboluminescence if you have high-speed capability.

More Triboluminescence Examples | Candy Spark-in-the-Dark

You breathe oxygen, yet air is mostly nitrogen. You need nitrogen to live and encounter it in the foods you eat and in many common chemicals. Here are some quick facts about this element. You can find detailed information about nitrogen on the nitrogen facts page.

1. Nitrogen is odorless, tasteless, and colorless.

2. Nitrogen gas (N₂) makes up 78.1% of the volume of the Earth's air.

3. Nitrogen is a nonmetal.

4. Nitrogen gas is relatively inert, but soil bacteria can 'fix' nitrogen into a form that plants and animals can use to make amino acids and proteins.

5. The French chemist Antoine Laurent Lavoisier named nitrogen azote, meaning without life.

6. Nitrogen was sometimes referred to as 'burnt' or 'dephlogisticated' air, since air that no longer contains oxygen is almost all nitrogen. The other gases in air are present in much lower concentrations.

7. Nitrogen compounds are found in foods, fertilizers, poisons, and explosives. Your body is 3% nitrogen by weight.

8. Nitrogen is responsible for the orange-red, blue-green, blue-violet, and deep violet colors of the aurora.

9. One way to prepare nitrogen gas is by liquefaction and fractional distillation from the atmosphere.

10. Nitrogen has a valence of 3 or 5.

Photo: Nitrogen in a gas discharge tube glows blue-violet. This color is commonly seen when air is ionized by lightning. (Jurii, Creative Commons)