Final Exam Review

15)  Give chemical formulas for the following compounds:


a.  cobalt (II) acetate:
CO(C₂H₃O₂)2


b.  hydronitric acid:
H3N
c.  aluminum dichromate:
Al2(Cr2O7)3


d.  dinitrogen pentoxide:
N2O5


e.  cesium carbonate:
Cs2CO3


f.  magnesium chlorate:
Mg(ClO3)2


g.  lead (II) nitride:
Pb₃N₂


h.  acetic acid:
HCH3COO






31)  Think of a topic or question you think should have been covered


Like many, I had trouble with sig figs when working with pH and pOH, so I thought more clarification would be helpful.


pH=-log(H)
(H: morality)


#total sig figs morality= # sig figs AFTER decimal for pH and pOH




example:


pH=-log(.0228)
     = 1.642


-.0228 has 3 sig figs allowing the answer to have 3 sig figs AFTER the decimal


*the concept is applied to the reverse as well


H=10^-pH
   = 10^-4.82
   =1.5 x 10^-5 M


-The pH only has 2 sig figs AFTER the decimal => the molarity has a TOTAL of 2 sig figs


*The same rules apply to pOH

The Everlasting Chernobyl

Overview

On April 26, 1986 a systems test was being conducted at the Chernobyl Nuclear Power Plant in Ukraine.  It was on this day, the worst nuclear disaster in history occurred when reactor number four exploded causing the graphite moderator to catch fire, sending a plume of smoke and ash containing radioactive material into the air. 

What is a Nuclear Reactor?

http://www.whatisnuclear.com/articles/nucreactor.html

A nuclear reactor houses the process of nuclear reactions through fission.  The core is where all the nuclear power is kept, and where the energy begins.  In nuclear fission, neutrons start a reaction where the nucleus of atoms split, and each time a nucleus splits it created more neutrons thus creating more atoms that split and continue this cycle.  When the nuclei split, they release energy in the form of heat.  The heat is transferred to the steam generator when the coolant, most of the times water, is passed through the core, heating up and creating steam.  This steam activates the turbine which in return activates the generator which gives off most commonly electricity.  However, nuclear reactors are also used to generate aircraft carriers or submarines, imaging for cancer treatment, and for research.  Several precautions are taken at these reactors.  At some plants, there are cooling towers.  The towers serve as an outlet for any excess heat that can not be converted to energy.  Secondly, some nuclear reactors have a dome covering the entire reactor as a secondary effort to reduce the risk of disaster.  Unfortunately, Chernobyl had no such cover.

What went Wrong?

The crew at Chernobyl was running a test to see how long the turbines would continue operating after losing a major power source.  This same test had been run the year prior, but revisions had been made since and this systems test was going to affirm the improvements.  Several vital mistakes lead to the catastrophe Chernobyl is today.  To begin with, the crew members were not trained well and overlooked major safety precautions.  The biggest mistake they made was disabling the automatic shutdown.  As soon as the operators realized the test wasn’t going as planned, it was too late.  The control rods created too much energy making them extremely hot causing steam to be over produced.  The graphite moderator was damaged, and the atoms could not be slowed down to prevent the over production of energy. The pressure was too great resulting to the rupture of the fuel channel, causing a steam explosion and the release of fission products.

(video of glowing graphite)

Effects

• The plume of smoke created by the explosion spread radioactive material
• In the immediate days following, 28 people died due to exposure to radiation, but it can not be determined how many people’s deaths are indirectly associated to the events at Chernobyl
• People were unaware of how severe the health risks are associated with radiation.
• The radiation affected many aspects of the victims lives, including their air and what they ate and drank, which in the end affected themselves. (see picture below)
• 4300 square kilometers were evacuated due to the unsuitable living conditions
• However, more than five million are currently living in areas that were affected by radiation from Chernobyl
• A concrete cover was placed over reactor 4 to allow the others to remain in use and a New Safe Confinement structure is set to be completed by 2014
• 200 tons of radioactive material still remain under the cover
• Raised awareness of nuclear safety 

http:/www.world-nuclear.org/info/chernobyl/inf07.html 

Similarities to Japan

Given the recent event in Japan, the nuclear reactor there is being compared to Chernobyl.  There are some similarities, but many differences as well.  When the tsunami hit Japan, the reactor was shutdown and safety rods were put in the core as a safety precaution.  Japan was able to foresee a problem and reduce the potential devastation.  However, Japan is facing the same problem that destroyed Chernobyl.  There is too much energy that is overheating the fuel rods, posing the risk of the rods melting and exposing radioactive material.  The key difference is that Chernobyl was a mechanical problem, and the situation in Japan was caused by a natural disaster.  While Chernobyl and the nuclear reactor in Japan share some similarities, nothing as traumatic as Chernobyl will happen in Japan.

Should America be Worried?

There are obvious concerns of radiation reaching America.  While this is a common initial thought, scientists assure Americans that they are not at risk.  Even if people carry radiation from overseas back, it would not be a harmful amount and no more than a chest x-ray would have.  Scientist say there is no reason for Americans to be worried.  

Works Cited

“Chernobyl Accident.” World Nuclear Association. N.p., n.d. Web. 4 Apr. 2011. <http:///www.world-nuclear.org/‌info/‌chernobyl/‌inf07.html>.

Hyper Physics. N.p., n.d. Web. 4 Apr. 2011. <http://hyperphysics.phy-astr.gsu.edu/‌hbase/‌nucene/‌cherno.html>.

Kavanagh, Jim. CNN. N.p., 17 Mar. 2011. Web. 6 Apr. 2011. <http://news.blogs.cnn.com/‌2011/‌03/‌17/‌whats-being-said-about-radiation-danger-to-u-s-from-japanese-nuclear-plant/>.

Marder, Jenny. “Japan’s Nuclear Crisis: Does it Compare the the 3 mild Island, Chernobyl?” PBS Newshour. N.p., n.d. Web. 6 Apr. 2011. <http://www.pbs.org/‌newshour/‌rundown/‌2011/‌03/‌cooling-system-fails-at-nuclear-reactors-fuel-talk-of-past-disasters.html >.

“Nuclear Reactor.” What is Nuclear. N.p., 2011. Web. 6 Apr. 2011. <http://www.whatisnuclear.com/‌articles/‌nucreactor.html >.

“Scientific Facts of the Chernobyl Nuclear Accident.” Green Facts. N.p., n.d. Web. 6 Apr. 2011. <http://www.greenfacts.org/‌en/‌chernobyl/‌index.htm >.

Extra Credit!

Ionic vs. Covalent

Would you rather be an ionic or covalent bond...?

Cyrus: Covalent because network solids are very strong

Christina: "Ionic because I want to be strong"

Marcy: "Ionic because I don't like to disclude people."

Kellye: "Covalent because I could be a gas and could fly."

Em Sher: "Covalent because sharing is caring."

Cate: Ionic in order to be stronger

Kira:  Ionic because they have stronger bonds with their neighbors.

Madison: Covalent "'cause it starts with a c..."

Abby:  Ionic because it's stronger.

Kelsoe:  Ionic because it is stronger so it is hard to break apart, whether melted or boiled.

Will: Ionic because they are stronger

Emily H:  Ionic because it's harder to break

Puja:  Ionic because it's harder to break

Michelle: Ionic because of its high melting and boiling point




Haiku

Combine non-metals
Electrons distributed
Achieve noble gas

Poly Atomic Ions are EVERYWHERE...

In makeup foundation...

1) Zinc Oxide

2)  Iron Oxide

In Advil...

3)  Potassium

In eyedrops...

4)  Magnesium Chloride

5)  Calcium Chloride

6)  Potassium Chloride

7)  Zinc Chloride

8)  Hydrochloric Acid

In Hydrogen Peroxide... non other than...

9)  Hydrogen Peroxide!!

In scented powder...

10)  Magnesium Carbonate

*To see the other 10 see Michelle's blog!!

Midterm Review Question #8

8) Explain the difference between chemical properties.  Describe some of the physical and chemical changes involved in cooking.

Chemical:
    -Produces matter different from original composition in a chemical change that can't be restored to                        
original state.

Physical:
    -Can be observed and measured without changing substance's composition and can be restored to original state.

Cooking Example:
    -When baking a cake a key ingredient is baking soda which causes a chemical reaction enabling the cake to rise.  This is chemical because the cake can never be turned back into the same batter.

Rutherfords Gold Foil Experiment

In 1909 Rutherford's gold foil experiment changed the way people viewed the atom forever. The experiment was conducted at the University of Manchester by Hans Geiger and Ernest Marsden under the direction of Ernest Rutherford. Rightfully so, this experiment is also known as The Geiger- Marsden experiment. This was revolutionary in that it proved for the first time, the existence of the atomic nucleus, thus killing the idea of the plum pudding model. Geiger, Marsden, and Rutherford's work will be studied forever.

         

The Plum Pudding Model composed by J.J. Thomson said that negative electrons were placed throughout and everything else (the pink) was positively charged "pudding" to balance the negative electrons.

The experiment was set by placing a particle emitter that would shoot particles made by radioactive decay of radium directly to a thin sheet of gold foil. Gold Foil was used because it is inert and malleable. In order for the particles to go through the material, it had to be really thin and gold was the perfect metal. Around the particles that would shoot toward the gold foil there was a circle of zinc sulfide which would detect when and where the alpha particles would deflect.

Rutherford hypothesized that the particles would pass straight through the foil or at most only deflect a couple of degrees. If this had occurred, it would have measured the distribution of charge through the "plum pudding" atom. This assumption was based on the theory that positive and negative charges were spread evenly through the atom, thus making their forces weak allowing for very little, if any deflection.

What ended up happening was the slit in which the particles were passed through, when made larger (greater than two nanometers), more particles were able to get through and the majority of these particles passed straight through the foil. Only one out of 8,000 were deflected at very dramatic angles. These angles were even greater than 90 degrees and in some cases the particles completely back fired.

In conclusion, this allowed Rutherford the prove J.J. Thomson's plum pudding model false.  Rutherford found that an atom is mostly made up of empty space with a concentrated charge in the middle.  He was able to conclude this because the majority of the particles passed through the empty space of the atoms and were not noticeably deflected, but the positive charge of the particles would repel against the one focused area of positive electrons in the atoms.  The focused and concentrated area that was discovered was named the nucleus.  Rutherford along with Geiger and Marsden came up with the following model of an atom.  It is because of these scientist curiosity that the model of an atom kept evolving and became more accurate.


                                           

<a href="http://www.wordle.net/show/wrdl/2530981/rutherfords_gold_foil_experiment" 
    title="Wordle: rutherfords gold foil experiment"><img
    src="http://www.wordle.net/thumb/wrdl/2530981/rutherfords_gold_foil_experiment"
    alt="Wordle: rutherfords gold foil experiment"
    style="padding:4px;border:1px solid #ddd"></a>

Sources:

• http://en.wikipedia.org/wiki/Rutherford_gold_foil_experiment 
• http://en.wikipedia.org/wiki/Plum_pudding_model 
• http://micro.magnet.fsu.edu/electromag/java/rutherford/ 
• http://reich-chemistry.wikispaces.com/file/view/Rutherford_gold-foil_experiment.jpg/146838757/Rutherford_gold-foil_experiment.jpg 
• http://en.wikipedia.org/wiki/Plum_pudding_model
• http://www.youtube.com/watch?v=5pZj0u_XMbc&feature=related 
• http://en.wikipedia.org/wiki/File:Rutherford_gold_foil_experiment_results.svg 
• http://www.uni-kiel.de/ps/cgi-bin/forscher/geiger-1.jpg 
• http://www.chemteam.info/Gallery/Marsden-2.GIF 
• http://mysciencearticles.com/images/ernest-rutherford.jpg 
• http://www.rsc.org/chemsoc/timeline//pages/1911.html
• http://wiki.answers.com/Q/Why_gold_foil_is_used_in_rutherford_experiment 
• http://wiki.answers.com/Q/In_what_year_did_Rutherford_do_the_gold_foil_experiment 
• http://www.cfo.doe.gov/me70/manhattan/images/AtomLabeled.gif 

The Physical and Chemical Properties of a Penny

         The penny, something we use everyday, but never take the time to examine.  A penny has many properties, both chemical and physical, that are not always apparent the the naked eye.  Based on the year the penny was made, there are a couple factors that that could cause different results.  For instance if the penny was made between 1944- 1982, then it is made of 95% copper and 5% zinc, while if made after that, the penny will be made of 2.5% copper and 97.5% zinc.  For experimental purposes, I chose to focus more on the penny made before 1982 that had a larger amount of copper in it.  The penny possibly the most simple and basic form of money has more properties than one would have ever thought.

Physical Properties


All of the properties listed below are physical because the compound itself changes, but nor the chemical composition.

• Weight:
• Before 1982: 3.1 g
• After 1982: 2.5 g
• Volume: 360 mm3
• Color: A copper color that loses its sheen over time.
• Circumference: 19mm

A smashed penny's weight and volume would stay the same, but it circumference would be changed.

•  Smell: A copper/ iron smell similar to blood

Chemical Properties


All of the following properties are chemical because they involve a chemical reaction that can never be undone.

• By putting a penny in bleach, along with cleaning the penny and removing some of the rust, dirt, ect., it produced a gritty white material on the penny.

• By putting a penny in water it will eventually rust causing a chemical reaction.

• By putting a penny in jewelry cleaner it removed most of the rust, dirt, and made the penny shinier.

The older penny's results were much
more noticable. The cleaner brought the penny
 back closer to its original state.

• When i put a penny in coke there were signs that corrosion had started.  Based on my research if i had a longer period of time for the penny to sit in the coke the corrosion would be so great that the penny would dwindle down to nothing.

The older penny was the one that had shown the most progress thus far.

• When I covered the penny with vinegar and left it over night, a green copper acetate formed much like the one on the Statue of Liberty.