Zunic,+Samantha

​Coins and Chemistry The article I read was Coins and Chemistry. It relates to chemistry because of the different metals used in coins. One thing I found interesting was that coins used to be made of gold, silver and copper. All coins in circulation today are called alloys. An alloy is a homogenous mixture of two or more elements, one of them being a metal. The bronze alloy today includes 95% copper, 4% tin, and 1% zinc. Pure gold and silver are very soft so they wouldn’t be able to handle circulating everyday.

Samantha, Great post! 5 big stars! MW

Crude Oil I learned that crude oil is useless as a mixture so it has to be distilled for use. The first fraction is collected at 40 degrees Celsius, but the second has to be heated at a higher temperature. Different hydrocarbons condense at different temperatures. This relates to class because we’re learning about distillation and which elements can be distilled. Crude oil can be distilled in larger amounts by a furnace. As the crude oil rises in a furnace, the temperature is decreased. Different types of oil are heated at different temperatures.

Samantha, You got it! 5 stars. MW

Redefining the Kilogram The kilogram is the mass measurement for one of the seven SI units. The official US kilogram is kept in a vault and has back-up copies which can be weighed for a fee. However the kilogram lost about 2/1,000,000 of its original mass when compared to the copies. So to redefine the mass, two constants were hypothesized. Planck’s constant describes the quantization of energy in matter and is related to mass. Avogadro’s constant is defined as the exact number of atoms in 12 g or a mole.

Sammy, Pretty basic but OK. 5 stars. MW

Where do Elements Come From? In 1054, there was an explosion, called a supernova, which released chemicals into space. This explosion released and created elements that are now in the periodic table. Elements that are heavier than iron are assembled by the stars through the capture of neutrons, or the "s" process. This process begins when an iron nucleus captures neutrons and creates a new nucleus. This nucleus can be stable or radioactive. If it is stable, the nucleus can absorb another neutron, but if it is radioactive it transforms into another nucleus. The "s" process is //s//low and happens inside a star before it explodes, but the "r" process is //r//apid and happens only at the same time of an explosion of a star. When an element becomes so heavy, it spontaneusly breaks apart by the process called nuclear fission.

Sammy, OK. Pretty much got it. 5 stars. MW

Mole Day Mole Day celebrates​ Avogadro’s findings about the existence of atoms and his number is the same as the mole. The mole is a constant of the SI units. The mole relates to chemistry because it is what scientists use to count things. One mole is a mass that is equal to the atomic mass of a molecule. One mole of any substance includes Avogadro’s number. Avogadro wasn’t given credit for his work until after his death. Mole Day is celebrated on October 23rd from 6:02 a.m. to 6:02 p.m. every year.

Sammy, OK. Good synopsis. 5 stars. MW

Dust Explosion I thought it was crazy that dust and sugar were the cause of an explosion. When the settled dust is disturbed it gets mixed with the oxygen in the air, and it triggers more explosions. This relates to the demo we did in class with the yellow powder that burned on the surface. When the dust particles are smaller, there is more surface area and it will burn faster. In plants, the particles get decomposed and collect; a simple spark can cause explosions. I was kind of unsure about how the explosion was initially started. Did the sugar just catch on fire? Just curious.

Sammy, I think it could have been static electricity. Apparently it didn't take much to get it started but then it cascaded into a chain reaction! 5 stars. MW

Helium Balloons In this article about helium balloons, I learned that there is a force called the buoyant force that acts like the opposite of gravity. The buoyant force is very small which is why it isn't very noticable. I was interested by the fact that the buoyant force makes things weigh more than they actually do. Something I'd previously learned was that the balloon floated up because of density. Also, gas molecules exert pressure in all directions. I didn't know that the buoyant forces acting left and right even each other out, but the forces acting up and down add up to an upward force. Prior to reading, I knew the pressure from the atmosphere decreases at higher elevations.

Sammy, The buoyant force actually makes things weigh less. Good stuff otherwise! 5 stars. MW

Motion Detectors In this article I learned that a photo sensor is anything that senses light. I think it’s interesting how our eyes are a type of photo sensors. We were talking about this in class how the eye absorbs light and it goes through to the brain and you see light! I learned how motion detectors work, for example photo sensors are used in all the motion detectors described in the article. The one type of detectors I recognized. It works by sensing when an object passes through it. This type of motion detector reminded me of the red laser beams in spy movies. In addition, I learned about the photoelectric effect. This is when a light of sufficient energy is shined on a surface; it can cause electrons to be expelled. Lastly, I knew that light behaved like particles, because I remember talking about it in class.

Sammy, Great stuff! 5 big stars! MW