It's All About Chemistry

[jamesbond]

. . . . . . . . . . . . .

[lovemarie]

. . . . . . .. . . . . . .

[jamesbond]

. . . . . . . . . . .

[lovemarie]

. . . . . . . . . . . .

[jamesbond]

^ eyun ow! sel healing rubber tyres created.. sana nga mailabas na sa market yan para wala ng flat tyre sa road trips be it long or city driving.... if and when matuloy yan, imagine it would lessen the perils of changing flat tyres especially at night, less crime and less hassles.... nice share mam...

[naruto789544]

interesting... so batteries can be made from a type of mushroom... a new sunscreen would be a welcome for all... with regards to anti bacterial soap, that's bad news for companies...

[jamesbond]

. . . . . . . . . . . . . . .

[lovemarie]

. . . . . . . . . . . .

[jamesbond]

. . . . . . . . . . . .

[lovemarie]

Selenium is a member of the chalcogen family. The chalcogens are elements in Group 16 (VIA) of the periodic table. The periodic table is a chart that shows how chemical elements are related to one another. Other chalcogens are oxygen, sulfur, tellurium, and polonium. The name chalcogen comes from the Greek word chatkos, meaning "ore." The first two members of the family, oxygen and sulfur, are found in most ores.

Selenium is a metalloid. A metalloid is an element that has some characteristics of a metal and some of a non-metal.

Selenium and tellurium are often associated with each other. They tend to occur together in the Earth and have somewhat similar properties. They have many uses in common. In recent years, some important new uses have been found for selenium. It is now used in the manufacture of plain paper photocopiers and laser printers, in photovoltaic cells that convert sunlight into electricity, and in X-ray systems for medical applications.

The miracle of copying
W e sometimes forget what an amazing step forward the invention of the copy machine was. Hundreds of years ago, making a copy of a document was a long, difficult process. Some people spent their whole lives making copies of important documents. Each copy was written out by hand. The process was not only dull and monotonous, but it also resulted in many errors.

Even thirty years ago, copying was slow and difficult. For example, carbon paper allowed a person to make one or more copies while writing or typing. But every error had to be corrected on every copy. The copies were often messy and difficult to read.

Mimeograph machines made it possible to reproduce dozens of copies in a few minutes, but required handwritten or typed originals. The final product was printed in purple.

Then came the photocopy machine. Copies could be made by simply placing the original on a glass cover and pushing a button. What goes on inside a copy machine to make this happen?

An essential part of a photocopier is a drum-shaped unit or a wide moving belt. Fine selenium powder is spread on the surface of the drum or the belt. An electric charge is then applied to the selenium.

Another part of the photocopy machine consists of a set of mirrors. When the machine's "Copy" button is pushed, a bright light shines on the page being copied. The light reflects off the white parts of the page. But it is not reflected off the dark parts, such as text or images. The light reflects off the mirrors to the drum or belt.

Selenium is important because when light strikes the charged selenium, the charge disappears. The sections on the drum or belt struck by light have no charge. The sections not struck by light continue to have a charge.

Next, a toner is spread out over the surface of the drum or belt. A toner is usually finely-divided carbon. It sticks to the areas that still carry an electric charge. But it does not stick to the selection without a charge.

Finally, a piece of paper is pressed against the drum or belt. The toner sticks to the paper. A blast of heat causes the carbon to melt and stick tightly to the paper. A copy of the original document is produced by the machine.




www.chemistryexplained.com

[jamesbond]

ah ok... kaya pala "xerox" cguro ang term na alam natin.... now i know... hmmm... galing talaga ng thread na ito.... +like po dito...

[lovemarie]

  2015 Theme: May the MOLES Be With You
Print
What Is Mole Day?
Celebrated annually on October 23 from 6:02 a.m. to 6:02 p.m., Mole Day commemorates Avogadro's Number (6.02 x 1023), which is a basic measuring unit in chemistry. Mole Day was created as a way to foster interest in chemistry. Schools throughout the United States and around the world celebrate Mole Day with various activities related to chemistry and/or moles.

For a given molecule, one mole is a mass (in grams) whose number is equal to the molar mass of the molecule. For example, the water molecule has an molar mass of 18, therefore one mole of water weighs 18 grams. Similarly, a mole of neon has a molar mass of 20 grams. In general, one mole of any substance contains Avogadro's Number of molecules or atoms of that substance. This relationship was first discovered by Amadeo Avogadro (1776-1858) and he received credit for this after his death.


Mole Day Activities

Whenever you choose to celebrate it, Mole Day is a great day to think about chemistry in general and the mole in particular. Here are some Mole Day activities for you:

~Determine how much aluminum foil you would need to make a 0.5 mole aluminum sculpture (of a mole, if you like). Weigh out the foil and get creative.
 
~Write your own mole joke. Examples of mole jokes include:
Where did Avogadro stay on is vacation? A mole-tel.
What do chemists wear when it's cold? Ther-mole underwear.

 
~~Make up a song about the mole. You should get bonus points if you make a video and upload it to YouTube.
 
~Determine how much water is in one mole of water. Can you drink that amount?
 
~Experimentally determine Avogadro's number.


How Did Mole Day Get Started?

Mole Day traces its origins to an article that appeared in The Science Teacher magazine in the early 1980s about a high school chemistry teacher's reasons for celebrating the day. The idea for Mole Day took root. The National Mole Day Foundation was formed on May 15, 1991. The American Chemical Society plans National Chemistry Week so that Mole Day falls within the week. Today Mole Day is celebrated around the world.


-credits to the source

[jamesbond]

Melting Metal With Magnets

the Science : The copper wire has a significant amount of AC electricity running through it, causing it to act like a really strong electromagnet. In the metal slug, eddy currents form due to the magnetic field the copper wire is causing while the copper wire has high frequency AC flowing through it. The metal slug’s electric resistance causes a portion of the electric energy to turn into heat, but the heat builds up until the metal slug becomes white hot and melts.

[lovemarie]

. . . . . . . . . . . . .

[jamesbond]

Orange LED Light In Liquid Nitrogen

The Science: When an LED is immersed in liquid nitrogen, the electrons lose a lot of thermal energy, even when the light isn’t turned on. When this happens, the band gap in the semiconductors increases. Since this gap is increased, when electrons in the conduction band fall to the valence band, they emit a higher energy light, meaning the light emitted has a shorter wavelength and a higher frequency. This is why we see the orange light turn into colours that are higher on the electromagnetic spectrum when it is frozen in the liquid nitrogen.