Tuesday, May 17, 2011

Exam Review: Question #24

24. Gas Laws:

a. A gas has a volume of 590.0 mL at a temperature of -55.0 degrees C. What volume will the gas occupy at 30.0 degrees.
1. This problem requires Charles' Law: V/T1 = V2/T2

V1= 0.590 L
T1= -55.0 C + 273.15 K = 218.2 K
V2= ?
T2= 30.0 C +273.15 K =303.2 K

V2=V1(T2)/T1 V2=(0.590L)(303.2K)/(218.2K)
V2=0.819 L

b. A gas occupies a volume of 140.0 mL at 35.0 degrees Celcius and 97 kPa. What is the volume of the gas at STP (standard temperature and pressure)?
*requires the combined gas law

Data: Formula:
V1= 0.140L P1V1/T1 = P2V2/T2
T1=35.0 C + 273.15 K= 308.2K  (97 kPa)(0.140 L)/308.2 = V2(101.325 kPa)/273.15 K
P1= 97kPa  V2= (97)(0.140)(273.15)/(101.325)(308.2)
T2=273.15K V2= 0.12 L
P2=101.325 kPa

c. If 20.0g of O2 is used in a combustion reaction with excess hydrogen, what volume of water vapor will be produced at a pressure of 825mmHg and 225 degrees Celcius?

2H2 (g) + O2 (g) > 2H2O (g)
g of O2= 20.0g
V of H2O=?
T=225 C +273.15 K= 498K

Step 1: convert 825 mmHg to atm
825mmHg x 1 atm/760.0 mmHg = 1.09 atm

Step 2: convert grams of oxygen gas > moles of oxygen gas > moles of H2O

20.0g O2 x 1 mol/32g x 2 mol H2O/ 1 mol O2 = 1.3 mol H2O

Step 3: Solve for Volume of water vapor
(use ideal gas law> PV=nRT)

V=(1.3 mol H2O)(.0821Latm/molK)(489 K)/1.09atm
V=48.8 L H20

Tuesday, April 5, 2011

The Nuclear Meltdown at Chernobyl

The Nuclear Meltdown at Chernobyl
How nuclear Plants Work:

·      Nuclear reactors are used to create heat by splitting atoms of elements, usually Uranium 235. This heat generated by the reactor is used to produce steam which turns a turbine that powers a generator. This generator creates electricity. Within the core of the nuclear reactor, fuel rods are inserted to control how much heat is being created within the reactor. (1) These fuel rods take away neutrons produced by the reactor to cool it down. There are also pressurized water-coolers that are used to cool down the reactor. (2) 

     Chernobyl Reactor:

       The Chernobyl reactor was a RBMK-1000 Soviet powered reactor near Pripat, Ukraine (3). This reactor is different because it was intended for plutonium and power production (2). This used a graphite moderated reactor that used water only for cooling. This reactor also used a Graphite moderator: graphite blocks that surrounded and separated the pressure tubes (the graphite slowed down the neutrons released during fission so that the fission chain reaction could be maintained). The  most dangerous part about this nuclear power plant was that it's Promt-Temperature Coefficient was positive.
                    Promt-Temperature Coefficient:
                             1. Being positive means as the reactor gets hotter, it gets more reactive and its power             increases which is very dangerous (3)
                             2. Most Plants are negative which means that the hotter the core gets, the more it wants to shut itself down (3)

      Another flaw in the Chernobyl reactor was its design of Control Rods. These control rods contained a poison (either Boron or Hafnium) that was inserted into channels between the graphite moderator and the Uranium to absorb neutrons and slow down the reaction. But, the tips of these control rods was not Boron poison, it was graphite. This means that control rods briefly increased the power of the reactor before bringing the reactor’s power, which was also dangerous. (3)
·   (7)
·     The Disaster at Chernobyl: 

     The disaster at Chernobyl occurred on April 26, 1986. On this particular day, they had scheduled a test on reactor 4 of the Chernobyl complex. They were trying to figure out how long it would take to cool the reactor if they shut it down using only the residual steam and coasting turbines for power to run the coolant pumps. (U.S. doesn’t allow these tests). In order to run the tests they had to bypass several automated safety systems (which violated protocol) which was strongly objected by the reactor operators but, an engineer was in charge. (this is one of the human mistakes, why would an engineer lead a test when it should be someone who is familiar with the reactor, like a reactor operator?)  This experiment was done several times before unsuccessfully but this time there was an 12 hour delay and they disabled safety systems. During this test the reactor was run down to a low power and held there for the experiment. A call came in ordering them to delay the experiment for several hours because of a sudden increase in power demand on the grid (nearly 12 hours). Lower power mean fewer neutrons in the core. Then the Xenon-135 started to build up in a highly accelerated rate and the power dropped further. The workers then began to withdraw the control rods in an attempt to stay at power (but the tips weren't Boron poison, they were graphite). They turned on extra cooling pumps, which cooled the core which allowed the power to drop even more (at this point they had a reactor held by low to no power by cold water and burnable poison with all of its control elements removed).  When they shut off the steam supply to the turbines, the flow of water slowed within the core increasing heat and raising reactor power because of their positive temperature coefficient. The reactor’s power increased so rapidly that someone his the SCRAM button or the emergency shutdown button. Now the graphite tips of the control rods quickly drove into the reactor, the moderator section filled the space between the fuel and further increased the reaction; this caused so much more power and heat that a feedback loop chain reaction took place. The heat and power increased so rapidly that there was a steam explosion that blew the 1,200 ton reactor head off the core and through the roof of the building.  The highly radioactive molten fuel and burning graphite was ejected into the atmosphere. (3)
     Long Lasting Health Effects: 
     The explosion triggered release of radiation into environment. There were 28 firemen and workers that died from acute radiation exposure. There was a huge increase in thyroid cancer and diagnosis of down syndrome. There were also chromosomal aberrations (chromosomes were messed up in DNA) and Neural Tube Defects (affects spinal cord, nervous system, and brain). Restriction of food even after 25 years.

     New Safety Precautions:
         Many new safety systems were created after Chernobyl in order to make sure that this never happened again. The Passive nuclear safety  system was created incase all systems fail. Pebble bed reactors were designed so that the complete loss of coolant for an indefinite period doesn’t cause a meltdown. They now have 3 sets of emergency diesel generators along with new emergency cooling systems. (Wikipedia)
·      Fukushima: 
      During the Fukushima incident the reactors themselves were taken offline, and the coolant pumps were supposed to have received  power from offsite but this option was eliminated by the earthquake itself, which apparently cut off the external power to Fukushima. The earthquake also triggered a shutdown of the reactors, removing the obvious local source of power to the pumps. At this point, the first backup system kicked in: a set of on-site generators that burn fossil fuels to keep the equipment running.Those generators lasted only a short while before the tsunami arrived and swamped them, flooding parts of the plant's electrical system in the process. Batteries are in place to allow a short-term backup for these generators; it's not clear whether these failed due to the problems with the electrical system, or were simply drained. In any case, additional generators were slow to arrive due to the widespread destruction, and didn't manage to get the pumps running again when they did.As a result, the plants have been operating without a cooling system since shortly after the earthquake. Even though the primary uranium reaction was shut down promptly, the reactor cores have continued to heat up due to secondary decay products. So far the most long-lived radioactive materials at the site appear to remain contained within the reactor buildings. Radioisotopes have and continue to escape containment, but there's no indication yet that these are anything beyond secondary decay products with short half-lives. (4)
        Since the U.S. is so far away from Japan and the reactor hasn't distributed any major signs like Chernobyl, and even though it is giving off small radioactive material with short half lives, we shouldn't be worried. 

       Footnote Citations:
       (4) http://arstechnica.com/science/news/2011/03/understanding-japans-nuclear-crisis.ars/2  
       (5) http://www.google.com/imgres?imgurl=http://www.deakwan.co.cc/myblog/wp-content/uploads/2011/03/Chernobyl.jpg&imgrefurl=http://www.deakwan.co.cc/archives/335&usg=__mdWJQyi6NIsuucWqBZHNfbBCvhs=&h=274&w=280&sz=19&hl=en&start=0&sig2=LnMn9BL7HLnZRrwjS3uXLQ&zoom=1&tbnid=mQqWhr0Py5d4FM:&tbnh=129&tbnw=130&ei=pending&prev=/images%3Fq%3DChernobyl%2Bexplosion%26um%3D1%26hl%3Den%26client%3Dsafari%26sa%3DN%26rls%3Den%26biw%3D1189%26bih%3D582%26tbm%3Disch&um=1&itbs=1&iact=hc&vpx=926&vpy=113&dur=465&hovh=219&hovw=224&tx=158&ty=156&oei=ZeWbTZWrIYS30QHWk7jjAg&page=1&ndsp=19&ved=1t:429,r:6,s:0
       (6) http://www.google.com/imgres?imgurl=http://www.thomasnet.com/articles/image/chernobyl-disaster.jpg&imgrefurl=http://www.thomasnet.com/articles/hardware/hardware-failures&usg=__19bQGAVhAWCuAtblVO1sa-hdPWs=&h=799&w=715&sz=108&hl=en&start=0&sig2=E9OMO9cilQJnNzBtDw9Lxg&zoom=1&tbnid=dpCWzi02UMicoM:&tbnh=158&tbnw=153&ei=b-ObTdXZEYa20QHy6b3jAg&prev=/images%3Fq%3Ddisaster%2Bof%2BChernobyl%26um%3D1%26hl%3Den%26client%3Dsafari%26sa%3DN%26rls%3Den%26biw%3D1189%26bih%3D582%26tbm%3Disch&um=1&itbs=1&iact=hc&vpx=469&vpy=89&dur=3286&hovh=237&hovw=212&tx=165&ty=126&oei=b-ObTdXZEYa20QHy6b3jAg&page=1&ndsp=16&ved=1t:429,r:2,s:0
       (7) http://www.google.com/imgres?imgurl=http://holbert.faculty.asu.edu/eee460/rbmk.gif&imgrefurl=http://holbert.faculty.asu.edu/eee460/eee460.html&usg=__Ean0MhZFymrbvk26THEr-ZlKwo4=&h=421&w=600&sz=47&hl=en&start=0&sig2=o_NmD27J4BJ98dZzc81sUQ&zoom=1&tbnid=vIb6RnrQ0jnvKM:&tbnh=126&tbnw=180&ei=s-KbTfWgLbC60QHxueDmAg&prev=/images%3Fq%3Ddesign%2Bof%2BChernobyl%26um%3D1%26hl%3Den%26client%3Dsafari%26sa%3DN%26rls%3Den%26biw%3D1189%26bih%3D582%26tbm%3Disch&um=1&itbs=1&iact=hc&vpx=124&vpy=95&dur=141&hovh=188&hovw=268&tx=138&ty=126&oei=s-KbTfWgLbC60QHxueDmAg&page=1&ndsp=18&ved=1t:429,r:0,s:0
      (8) http://www.google.com/imgres?imgurl=http://scienceinseconads.com/cmsFiles/pageImages/Nuclear%2520reactor.jpg&imgrefurl=http://www.scienceinseconds.com/blog/Meltdowns&h=244&w=500&sz=22&tbnid=XumcMc9M-_z3aM:&tbnh=63&tbnw=130&prev=/search%3Fq%3Dnuclear%2Breactor%26tbm%3Disch%26tbo%3Du&zoom=1&q=nuclear+reactor&usg=__6wtSqlMnZ11Qlf7Hi_BF5MArU5I=&sa=X&ei=beubTYOYGvKw0QGTnfHlAg&ved=0CEUQ9QEwBQ
     (9) http://www.google.com/imgres?imgurl=http://www.smh.com.au/ffximage/2004/08/09/nuclear_wideweb__430x376.jpg&imgrefurl=http://www.smh.com.au/articles/2004/08/09/1092022409037.html&usg=__TLB0SyBqn5E5l6mhgO5RiFzcc_0=&h=376&w=430&sz=32&hl=en&start=0&sig2=L7vsQrtwd1uJksiQ1GL2Vg&zoom=1&tbnid=G_QnNF3NjHbseM:&tbnh=135&tbnw=167&ei=u-ubTeCNK-yG0QGK3LjjAg&prev=/images%3Fq%3Djapan%2Bnuclear%2Bplant%26um%3D1%26hl%3Den%26client%3Dsafari%26rls%3Den%26biw%3D1189%26bih%3D582%26tbm%3Disch&um=1&itbs=1&iact=hc&vpx=738&vpy=90&dur=430&hovh=210&hovw=240&tx=146&ty=104&oei=u-ubTeCNK-yG0QGK3LjjAg&page=1&ndsp=17&ved=1t:429,r:3,s:0


Sunday, December 12, 2010

If Your Cat Took Chemistry, Would She Eat This Stuff?


1. calcium hydroxide

        a. Ca(OH)
            b. Tropicana Orange Juice

2. zinc oxide
        a. ZnO
        b. Froot Loops

 3. potassium iodide                                                         
        a. KI
        b. Morton Iodized Salt
4. sodium phosphate
        a. Na3PO4
        b. Canadian Bacon
 5. sodium nitrite
        a. NaNO2
        b. Canadian Bacon

6. calcium chloride
        a. CaCl2
            b. Jalepeno Slices          
7. calcium carbonate
        a. CaCO3
        b. Silk Light 

8. magnesium oxide

        a. MgO
        b. Jif Creamy Peanut Butter 

9. copper (I) sulfate or copper (II) sulfate
        a. Cu2SO4 or CuSO4        
        b. Jif Creamy Peanut Butter

10. calcium phosphate
        a. Ca3(PO4)2
        b. Purina EN Dog Food
11. potassium chloride
        a. KCl
        b. Purina EN Dog Food 

12. sodium carbonate
        a. Na2CO3
            b. Ramen Noodles

13. potassium carbonate

         a. K2CO3
         b. Ramen Noodles

14. potassium nitrate 
          a. KNO3
          b. Pro Namel Toothpaste
15. sodium fluoride
          a. NaF
          b. Pro Namel Toothpaste

16. ammonium hydroxide
          a. NH4OH
          b. AmLactin Body Lotion

17. sodium chloride
          a. NaCl
          b. Halls Breezers 

18. manganese sulfate
          a. (II) = MnSO
              (III) = MnSO
          b. Advocare Shakes

19. ammonium chloride
      a. NH4Cl
      b. Bed Head Conditioner

 20. hydrogen peroxide 
       a. H2O2
       b. Crest 3D Whitening Toothpaste 


Friday, November 12, 2010

Mid Term Exam Review Question # 20

For this blog I was assigned question # 20(a,b, and c) on our exam review. The questions are....

a) What is the most common charge on an ion from Group 6A (group 16)?
b)What is the most common charge on an ion from the group 2A (group 2)?
c) Using your answer from b, where would you except a sudden jump among consecutive energies and why?

A) Group 6A or group 16 starts with the element O, or Oxygen. The most common charge on an ion that would form would be 2-. These elements form 2- ions because theses elements have a intensely high ability to add two electrons inorder to have the stable electronic configuration of a noble gas.

B) Group 2A or group 2 starts with the element Be, or berillium. The most common charge on an ion that form is 2+. These elements also want to have the stable configuration of a noble gas, so they take away 2 electrons inorder to get that electronic configuration.

C) Because the elements in group 2A form ions with a charge of 2+, there will be a sudden increase in ionization energy when you take away the 3rd electron, or IE3, from these elements. Because these elements for ions with a charge of 2+, a stable noble gas configuration, it takes an extreme ammount of energy to take away the next electron because these elements already have that stable configuration.

Wednesday, October 6, 2010

Ernest Rutherford's Gold Foil Experiment

For this blog assignment I decided to look deeper into the Experiment that founded the nucleus, the Gold Foil Experiment. When we were going over this experiment during class, I didn't really understand why the alpha particles were deflected and how this founded the discovery of the nucleus. If you click on the link to my glogster below, all you chemistry dreams will come true! Enjoy!

Here is a link to my Glogster!


Here is also a Youtube Video that further explains the Experiment:


After conducting my research I realized that the significance of this experiment was that current plum pudding model of the atom was incorrect and that because of the waythat the alpha particles bounced off the gold foil showed that the majority of the mass of the atom was concentrated in one small area (the nucleus). Since most of the positive particles continued on their original path undeflected, Rutherford assumed that the rest of the atom was made up of empty space. Rutherford termed his discovery "the central charge," and it is now called the nucleus. Rutherfords discovery lead to the Bohr model of the atom and the developement of nuclear physics.

Monday, September 13, 2010

Chemical and Physical Properties of a Jet-Puffed Marshmallow!


For this assignment I decided to observe the chemical and physical properties of a marshmallow. A marshmallow is a very common object that is essential to kid's daily lives. I chose this object because I never really thought of its chemical or physical properties. I just looked forward to shoving it into my mouth.

Chemical Properties:
1. Roasting the Mallow (Everyone's favorite)
As I roasted the marshmallow, and as it caught on fire it started to burn around the outside. When I burnt the marshmallow, it caused a chemical reaction, forming a new substance (the burnt part) and changing its composition.

2. Boiling Marshmallows with Malt Vinegar

To execute this experiment, I added some marshmallows to a pot and added some Malt Vinegar and boiled it. This produced a chemical reaction and the marshmallows evaporated.

3. Marshmallow in Nail Polish Remover
When I did this experiment, i filled a container up with nail polish and put the marshmallow in it. Nothing happened. Marshmallows do not react to nail polish remover.
4. Marshmallow in Hydrogen Peroxide
When I executed this experiment i put hydrogen peroxide in a small container. When I put the marshmallow in the container nothing really exciting happened. Marshmallows do not react to hydrogen peroxide.

5. Marshmallow in Kaboom
When I put the marshmallow in a small container of Kaboom, nothing really big happened. The only thing I observed was that it dissinegrated a little bit but not a lot.

Physical Properties:

1. Density: 0.37 g/ml
2. Diameter: 3cm
3. Squishy, foamy, and soft composition 
4. White color
5. Expands with heat:
I was curious of what would happen if I put marshmellows in the microwave. When I did they expanded and the insides turned gooey


In conclusion, the marshmallow was a tough object to pick. In fact, it hardly reacted to anything I put it in. I wish I would have picked an easier object. But atleast eating the roasted marshmallows was fun!