Tuesday, May 17, 2011

Final Exam Review: #20 and #31

20) A white powder is analyzed and found to contain 43.64% phosphorous and 56.36% oxygen by mass. The compound has a molar mass of 283.88 g/mol. What are the compound's empirical and molecular formulas?

$43.64 g P*\frac{1 mol P}{31.0 g P}=1.41molesP$
$56.36gO*\frac{1 mol O}{16.0 g O}=3.52 moles O$
$P_{1.41}O_{3.52}=P_{1}O_{2.5}=P_{2}O_{5}=empirical formula$
$2(31.0)+5(16.0)=142.0$
$\frac{142.0}{283.88}=\frac{1}{2}$
$empirical formula*2=molecular formula=P_{4}O_{10}$

31) A topic not covered by the final exam review is how a nuclear reactor works:
A nuclear reactor is basically a system of recycled water. The water is heated and is turned into steam which travels down a steam line to spin the blades of a turbine. The turbine then turns the shaft of a huge generator, where electricity is produced. The steam then cools down back into water and the cycle repeats. Control rods prevent the reactor from overheating and when they and the fuel rods are spent they are placed in a cooling tank called a "swimming pool".

Thursday, April 7, 2011

Chernobyl

Kira
April 7, 2011
Honor Bound
B6
The Accident at Chernobyl

Nuclear power plants produce electricity when the reactors split atoms of an element. The heat that the nuclear reaction emits creates steam. The steam then powers the reactor’s generator, which in turn creates electricity. The water in the reactor serves as a coolant that prevents the plant and reactor from overheating. The generator ignites the spark while the turbines turn it. Meanwhile, radioactive material heats water into the system in the reactor’s core.
In 1986, an accidental nuclear reaction occurred in Chernobyl, Ukraine due to a poor reactor design and ill-trained employees. Chernobyl lies just about one hundred miles north of Kiev on the border of Belarus and is situated near an artificial lake that once provided cooling water to the reactors. In the Chernobyl Power Complex there were four nuclear reactors of RBMK-1000 design. The Chernobyl 4 Reactor was built by 1983. At the end of a normal workday on April 25, the nuclear power plant was going to run a test involving the plant’s turbines. They wanted to find the amount of time that the turbines would spin to supply power to circulating pumps in case there were to be a loss of “main electrical power supply”.  The operators on the night before April 26 were to disable automatic shutdown mechanisms along with the emergency core cooling system that provides water for cooling the core in case there was an emergency. When an operator attempted to shut down the reactor, they noticed that it was unstable. The control rods’ design had caused a huge power surge when they were inserted into the Chernobyl 4 reactor. The reactor’s power was decreasing at a rate much quicker than planned for by the test operators because it was so late at night and they felt pressed for time. In result, fuel elements busted and fission built up in the core, which increased the generation of steam and pressure in the Chernobyl 4 Reactor. The water coolant could not work quickly enough and the increased pressure detached the reactor’s support plate, which in turn, jammed the control rods. To add to the chaos, the control rod tips were made of graphite and just added to the reaction. The reactor lost its coolant and became progressively hotter. The steam and the heat caused two explosions early in the morning of April 26, 1986. The explosions and fires lasted for ten days after the initial explosions, but radiation is still among the Ukrainian town today, as well as its surrounding lands. In the burning Chernobyl 4 Reactor, iodine-131 and cesium-137 were released. Luckily, iodine-131 has a half-life of eight days, so the radioactive isotope disintegrated shortly after the tragic accident. Unfortunately, however, cesium-137 has a half-life of thirty years and is still found in items such as food and soil today. The heavier debris rose up to about one kilometer in the air before settling near the nuclear power plant, but the lighter materials such as fission products were taken away and scattered by the wind. Hundreds of firemen arrived on the scene, but the first ones to arrive received the worst from the radiation. Within the first three months, thirty firemen and operators had died. There were 134 confirmed cases of acute radiation syndrome, which eventually killed 47 of the affected people.
Parts of modern-day Belarus, Russia, and Ukraine were greatly affected by the radiation. Five million people were in contaminated areas and unluckily, there are many ways in which a human being may be affected by the toxic radiation. First of all, the steam can scald someone. Also, radioactive fallout can cause thyroid cancer, mainly found in children. Surprisingly, just simply the fear of radiation can cause severe cases of stress. Another effect of the Chernobyl radiation is the contamination of locally grown food. To prevent inhalation of the contamination, local food is often thrown out in a fallout area, which decreases the amount of nutrients citizens have each day. Also, during the time of the Chernobyl tragedy, many women decided to have abortions due to the fear of having radiated contaminated fetuses. Symptoms of radiation poisoning may include nausea, vomiting, a brief appearance of no illness, headache, and fever. Late symptoms may include dizziness, weakness, fatigue, hair loss, low blood pressure, and the coughing up of blood. At the time of the incident, more than 100,000 people were evacuated from surrounding areas and some of the land today is still contaminated.
Fukushima, today however, in Japan has had more explosions in their nuclear reactors than Chernobyl did almost twenty-five years ago. Chernobyl’s RMBK reactors were Russian models (reaktor bolshoy moshchnosty kanalny) with the coolant of water, similar to Japan’s Light Water Reactors. However, Chernobyl it has been learned from the Chernobyl incident in places such as Japan to not use graphite as a moderator. Also unlike Chernobyl, Japan’s incident was cause by a natural disaster, a tsunami, whereas Chernobyl’s tragedy was a result of employee error and unstable reactor models. Also, the workers at the power plants at Fukushima did as instructed in case of an earthquake emergency, so they are not at fault. In Japan, the power that kept the cooling system running was shut off by the tsunami; therefore, the reactor overheated and caused explosion. Whereas Chernobyl was a badly executed safety test, Japan was simply a freak accident.

Works Cited:
“Chernobyl.” PBS.org. N.p., n.d. Web. 6 Apr. 2011. <http://www.pbs.org/‌wgbh/‌pages/‌frontline/‌shows/‌reaction/‌readings/‌chernobyl.html>.
“Chernobyl Accident.” World Nuclear Association. N.p., n.d. Web. 4 Apr. 2011. <http://www.world-nuclear.org/‌info/‌chernobyl/‌inf07.html>.
“Chernobyl Health Effects: Best Available Data.” Atomic Insights. N.p., n.d. Web. 6 Apr. 2011. <http://atomicinsights.com/‌1996/‌04/‌chernobyl-health-effects-best-available-data.html>.
“How Is Japan’s Nuclear Disaster Different?” National Geographic. N.p., n.d. Web. 7 Apr. 2011. <http://news.nationalgeographic.com/‌news/‌energy/‌2011/‌03/‌1103165-japan-nuclear-chernobyl-three-mile-island/>.
“How Nuclear Power Works.” How Stuff Works. N.p., n.d. Web. 7 Apr. 2011. <http://www.howstuffworks.com/‌nuclear-power.htm>.
“Preface: The Chernobyl Accident.” International Chernobyl Radiological Portal of the ICRIN Project. N.p., n.d. Web. 4 Apr. 2011. <http://chernobyl.info/‌Default.aspx?tabid=294>.
“Pressurized Water Reactor Diagram.” TVA. N.p., n.d. Web. 7 Apr. 2011. <http://www.tva.gov/‌power/‌wbndiag.htm>. Picture

Chernobyl 4 Reactor's control room

Wednesday, December 8, 2010

Chemistry is Everywhere

Here is my list of ionic compounds I found in everyday items. Enjoy...

1. magnesium oxide
MgO
Clif Bar

2. potassium iodide
KI
Clif Bar

3. chromium chloride
chromium (II) chloride: CrCl2
chromium (III) chloride: CrCl3
Clif Bar

4. sodium hypochlorite
NaClO
Clorox Clean-Up with bleach

5. manganese sulfate
manganese (II) sulfate: MnSO4
manganese (III) sulfate: Mn2(SO4)3
Glucosamine Medicine, Triple Strength

6. sodium chloride
NaCl
Opti-free Replenish Contact Solution

7. sodium hydroxide
NaOH
Clean & Clear: Morning Burst Facial Cleanser

8. potassium carbonate
K2CO3
Maruchan Instant Lunch Ramen Noodles (Chicken Flavor)

9. sodium carbonate
Na2CO3
Maruchan Instant Lunch Ramen Noodles (Chicken Flavor)

10. sodium phosphate
Na3PO4
Maruchan Instant Lunch Ramen Noodles (Chicken Flavor)

11. calcium carbonate
CaCO3
Swiss Miss Hot Cocoa Mix

12. calcium sulfate
CaSO4
Friendly Farms-Light Sour Cream

13. calcium chloride
CaCl2
Vlasic Kosher Dill Pickles

14. potassium chloride
KCl
Campbell's Tomato Soup

15. zinc oxide
ZnO
Mary Kay-Timewise Moisturizer

16. sodium fluoride
NaF
Crest Toothpaste

17. ammonium chloride
NH4Cl
Caress-Body Wash

18. magnesium phosphate
Mg3(PO4)2
Flintstones Complete Multimineral Supplement Vitamins

19. phosphoric acid
H3PO4
Diet Coke

20. sodium bicarbonate
NaHCO3
Arm & Hammer-Baking Soda

Tuesday, November 9, 2010

Exam Review: 21 c-d

c) Convert 22Mg to $\mu g$
$\frac{22 Mg}{1}* \frac{1*10^{6}g}{1 Mg}* \frac{1\mu g}{1*10^{-6}g}=2.2*10^{13}\mu g$

d) If a stack of ten 3.5 inch diskettes is measured to 34 millimeters high, and each disk has a mass of approximately 2.34 grams, how many kilograms would a stack of disks 12.34m high be?
10 diskettes=34mm=0.34cm=23.4g
1 diskette=2.34g
new height=12.34m=1234cm
(Answer: how many diskettes will fit x 2.34g)
$\frac{0.34cm}{10 diskettes}=0.034cm$ (disk height)

# of disks in new height=1234cm/0.034cm=36,000 (w/ sig figs)
# of disks x 2.34g=weight of new height=84,240g=84.24kg

Tuesday, October 5, 2010

Discovery of the Proton

In deciphering the composition of the atomic nucleus came many experiments. In order to do so, alpha-scattering experiments were popular among scientists. In the early 20th century, Ernest Marsden was curious as to what would happen if alpha rays came in contact with light nuclei. However, Marsden moved to New Zealand for work purposes in 1914, around the beginning of World War I. He was forced to leave his experiments unfinished. Ernest Rutherford decided to take over the experiment from him. However, throughout the war, Rutherford, as well as many other scientists, were preoccupied with figuring out how to detect submarines. From 1914 to 1918, Rutherford left his experiment with the alpha particles to join the war effort. As soon as he was able to, he picked up where he left off before World War I. Rutherford shot alpha particles into nitrogen gas and noticed peculiar reactions.
For his experiment, Rutherford had a brass box and placed a little glass tube inside at one end of the box. A zinc-sulphide scintillation screen was then placed by the glass tube. Then, radon gave off helium nuclei through the glass tube while the brass box was filled with nitrogen. There were then scintillations, or flashes of light, on the screen. Although there was no hydrogen at the beginning of the experiment, the flashes were definitely derived from hydrogen. Rutherford concluded that the nitrogen had disintegrated. Also, in conclusion, Rutherford was convinced from the evidence of his well-thought-out experiment that the hydrogen nucleus was an elementary particle due to the fact that the nitrogen nucleus was made of hydrogen nuclei. Ernest Rutherford named the particle the proton, deriving the word from the Greek word “protos”, which means “first”.
Because Rutherford discovered the proton through a series of steps in his experiment, scientists today are able to determine which chemical element an atom is. The number of protons in the nucleus is equal to the atom’s atomic number, which would not be relevant today without Rutherford’s historical discovery.

Rutherford’s experiment set-up:

Works Cited:

Monday, September 13, 2010

The Physical and Chemical Properties of an Eraser

I chose an eraser as my object to test on because it seemed like an object with not that many chemical properties, but I was determined to find at least one that would change it’s chemical make-up. The process that ended up doing so was the burning of the eraser. The eraser formed into black, or carbon, changing the chemical make-up of the Magic Rub Eraser. Out of the four other chemical properties I tested, none of the rest worked. I feel like a chose a challenging object that would not necessarily react to everything.
Phy1: The eraser’s size is 5.7 cm by 2.4 cm by 0.9 cm. Measuring the eraser using a ruler with a centimeter scale on it can prove this.

Phy2: Color- From observation, the eraser is an eggshell white color.

Phy3: Smell- From observation, the eraser is made of synthetic rubber but it smells like new plastic.

Phy4: Malleability- The eraser is not really malleable. It can bend one way at a 90 angle at most.
Phy5: Hardness- The eraser is soft but a solid, so the molecules are close together.

Chem1: Bleach- Nothing happened when the eraser and Clorox bleach came in contact with each other. There was not chemical reaction.
Chem2: Vinegar- When placed in vinegar, the eraser did not react chemically with the liquid. The vinegar just made the eraser the smallest bit more malleable.

Chem3: Fire- When I set the eraser on fire, it gave off a really strong scent of burning rubber. It smelled like there was a car race and the tires were all skidding. The eraser also changed to a dark brown color and shrunk. The eraser reacted chemically with the fire.
Chem4: Boil- When I boiled the eraser for a few minutes, it came out more malleable. It also gave off heat and a smell that smelled like burnt rubber, or car tires that had just skidded. There was no chemical reaction though.

Chem5: Rubbing alcohol- When I put the eraser in rubbing alcohol it became more malleable, but there was no chemical reaction.