Biesecker,+Alexis

Before I read this article, I knew that when mentos were put in soda, the soda would explode out of the bottle. I also knew that the more mentos you add to the soda, the explosion is going to be higher and stronger. I didn’t know why this happened, but from actually doing it just for fun myself, I learned this. The last thing I knew was if you put the cap back on the bottle before it explodes, it added more pressure and also made the explosion much larger. After reading this article I learned why the explosion actually happens. The amount of CO2 that can be dissolved in a single liter depends on the pressure of CO2 pushing on the soda’s surface. When you open the bottle, the pressure drops, the bottle is holding more CO2 than usual and it becomes super-saturated. If the temperature is too high, then the soda will lose its fizz. So that a regular bottle of soda does not explode, they make the inside of the bottles extremely smooth. This is so there are no nucleation sites or surface starters. The mentos may seem smooth, but really they have a lot of bumps and have an uneven surface, which adds a surface starter to the bottle. With an uneven surface the fizz starts with microscopic bubbles that are forced to shoot out of the top of the bottle. This is what causes the explosion between mentos and soda.

Alexis, OK. Looks very good! It's cool to learn about nucleation sites. 5 stars! MW

Video Response- September 19th

One thing I learned is that different hydrocarbons will separate at different boiling temperatures by using distillation. In this experiment they heated crude oil to try to separate the different components. They changed the temperature multiple times since each component boils at a different temperature. This means that the ones on the bottom will have a higher boiling temperature and then condense at that high temperature. The hydrocarbon with the lowest boiling point will rise towards the top. This happens because the lowest boiling point is the first to heat up, and so it will continue to rise throughout the experiment. Each temperature will separate the hydrocarbons. Using distillation is a separation technique that is very helpful when separating hydrocarbons.

Alexis,

Looks good! 5 stars. MW

Motion Detectors- Before I read this article, I knew that there were three types of motion detectors, which are infrared radiation, one that uses pulses and reflections, and one that measures the warmth of an object. From each of these things, the machine can tell whether or not something is there. I also knew that police use radio waves. I knew this because if they frequencies were higher, then it could become harmful. Finally, I also knew that bats are an animal that use detection to find their pray. Instead of using light to see, they use sound energy. One thing I did not know is that that sometimes even glass can block the detection of an object. I always wondered if an inside detector would "see" you if you're outside. Another thing I learned is that no matter what type of light there is, a detector can almost always be made. I didn't think this was possible at first because I thought if we couldn't see it, neither could a machine. Finally, I learned that the photoelectric effect was first observed by Heinrich Hertz in 1887. This surprised me because I didn't think that in the 1800's they would have enough knowledge to completely understand light and all the affects it has on objects. He was the one who tried to figure out why certain frequencies and intensities caused electrons to "fly."

Alexis,

Looks good! 5 stars. MW