Quickel,+Rebekah

August 29, 2010 Coins and Chemistry

I read the article about coins and found it quite interesting. I never knew that most coins made today are not actually made of silver or copper or gold but are made of cheaper materials and have a silver or copper coating on top of the coin. What confuses me is the fact that silver coins have a copper core thats covered in a silver coating while pennies are made of a zinc core with a copper coating. It seems that the mint companies are wasting more money by making all silver coins out of copper instead of making pennies out of pure copper. I also think that it is very strange that people would hoard a cetrain coin when the value of the metal it was made out of exceded that value of the coin. I didn't know that there was a specific act that was passed stating that all coins must be made out of copper, silver, or gold.

Rebekah, I think you'll find that modern coins don't have much if any silver in them. Copper prices have really gone up over the past few years also. Good post. 5 stars. MW

September 2, 2010 Redefining the Kilogram

I read Redefining the Kilogram. I found many interesting things. One is that scientists have been trying for centuries to perfect and find the exact SI measurments. Also I found that you have to have a measurment ratified before it can be called the official measurment. The most important thing that i found interesting was that we have a replica kilogram in the United States. We don't even use the metric system and we have a kilogram measurment!

Rebekah, That's a good point about us having a standard kilogram. I wonder if we have a standard pound? 5 stars. MW

September 17, 2010 Crude Oil

One thing that I found very interesting about crude oil is that it is useless as it is and has to be separated into the different hydrocarbons. I never really knew why everyone was saying that gas was really hard to find even though it is pumped out of the earth everyday. It makes a lot of sense that you only get a small amount of each fraction fro a large amount of crude oil since there are multiple types of hydrocarbons in crude oil.

Rebekah, We use so much oil that we are depleting the easily obtainable reserves. 5 stars. MW

Where do Chemical Elements Come From?

<span style="font-family: Georgia,serif;">Elements are formed inside stars, and supernovas are able to make elements heavier than iron. Everything in the universe was formed by elements from stars.

<span style="font-family: Georgia,serif;">Rebekah, <span style="font-family: Georgia,serif;">Good job! 5 stars. MW

<span style="font-family: Georgia,serif;">October 28, 2010 <span style="font-family: Georgia,serif;">Motion Detectors

<span style="font-family: Georgia,serif;">There are three types of motion detectors. One uses a light source and when something crosses the path of the light, it goes off. Another one send out pulse and when something passes infront of it, it changes the echo from the pulse and it goes off. The third moniters any infared radiation that passes by. When any warmth is detected, it goes off. Some animals also have a sort of motion detector ability. Snakes can detect infared radiation and it is how they see in the dark. Bats use ecolocation to find bugs to eat in the dark.

<span style="font-family: Georgia,serif;">Rebekah, <span style="font-family: Georgia,serif;">Clearly indicate 3 things you knew and three things you learned. 4 stars. MW

<span style="font-family: Georgia,serif;">December 8, 2010 <span style="font-family: Georgia,serif;">Sugar an Unusual Explosive

<span style="font-family: Georgia,serif;">A sugar factory in Savannah Georgia exploded when sugar dust got into the air and there was a spark. Something that I found interesting the article was that if anything is shredded enough it can blow up. This can relate to class because when something, like sucrose, is in the air and there is a spark, it will react with the oxygen in the air and explode. Also man other things beside sucrose, can explode when exposed to oxygen and a spark. Things like dust from coal, flour, different metals, plastics, and wood can explode and have exploded.

<span style="font-family: Georgia,serif;">Rebekah, <span style="font-family: Georgia,serif;">I tried this with talcum powder and nothing happened. Some dusts are not combustible. 5 stars. MW

<span style="font-family: Georgia,serif;">December 21,2010 <span style="font-family: Georgia,serif;">Helium Balloons

<span style="font-family: Georgia,serif;">I really liked this artice. One thing I found very important is that because of boyant forces, you weigh less than you actually do. Since you displace air, you weigh less, but if you were in a vacume, you would weigh more than your weigh outside of the vacume. Another important point is that the reason a helium balloon rises to the ceiling is because it has a negative weight when the boyance factor is added in. That is also why most gasses rise to the ceiling, they are less dense than air and have a negative weight. The most important point is that the molecules hitting the sides of the object cancle eachother out because they are both exerting the same amount of pressure. The amount of pressure on the top and bottom of the object will decide wheather it will rise or fall.

<span style="font-family: Georgia,serif;">Rebekah, Actually lots of gases sink in air. Pretty good summary. You might want to use spell check though. 5 stars! MW