Friday 3/21/14

Oh the week before spring break. Always a struggle.
These past few weeks I have learned that waking up on a Saturday morning for the Chemical Olympiad is a part of the AP Chemistry course. (#nerdstruggles). I learned there that I am actually a bigger nerd than I thought. I have also continued learned about equilibrium, chemistry style (different than biology style). And in government, we are learning about the realities of stock investing. You'd be happy to know that in "The Stock Game," I have invested in Starbucks.

I have recently completed BOTH of my books for English and their corresponding tests. Comer has not been easy on us lately, so I have also completed TWO more timed writings. This is exciting because I can now write a decent five paragraph essay in less than 40 minutes.

I plan to finish this monsterous 10 page packet you assigned and the next UT homework over the spring break...somehow. I also plan to get through the next days full of two practices before we leave for STATE! I plan on doing well, even with this stupid ankle. THEN I plan on reviewing for the AP test for the rest of the school year!

pH Lab

pH is the measure of the concentration of hydrogen ions in a solution and pOH is the measure of the concentration of hydroxide ions in a solution. A solution with a high concentration of H+ is considered acidic while a solution with a high concentration of OH- will be basic. On the pH scale of 1-14, 1-6 is considered acidic while 8-14 are basic and 7 being neutral.

In this lab, we found the pH of different buffers based on color using a universal indicator. By using a universal indicator in this lab, we were able to measure the pH of both acidic and basic solutions. Indicators change the color of solutions based on certain pH levels or concentrations. However, the colors may represent a range of close pH levels. Therefore, we must decide on a approximate pH, not exact. Once we observed how certain colors corresponded to certain pH levels, we could determine the pH of common household items.

Explore Lab: Intro to Equilibrium

In this lab, we were introduced to the reaction pertaining to nitrogen dioxide gas and dinitrogen trioxide gas.

2NO2 <---> N2O4

As we placed a test tube in the boiling water, it turned dark brown while test tubes in the ice turned to almost a colorless gas. The forward process was favored in the ice bath while the reverse reaction was favored in the hot bath. Therefore, there was a higher concentration of NO2 in the test tubes in the boiling water while there was a higher concentration of N2O4 in the ice. 

As we "explored," we placed test tubes back and forth from the boiling water to the ice bath. We observed the gas in the test tubes change with temperature. As we placed a tube from the ice into the boiling water, the gas began to turn a dark brown. We learned that the rate stays the same through out the reaction; however, we did shift the rate using change in temperature. As temperature changed, the reaction increased rate of formation of either NO2 or N2O4, based on the required activation energy. Since the forward reaction was induced with heat, we can conclude that the activation for this endothermic process is greater than that of the reverse reaction. 

The test tube at room temperature has a constant rate of the reaction in equilibrium. Concentrations of NO2 and N2O4 are kept at a steady and ongoing rate (ratio is 2:1 moles). 

Friday. 3/7/14

Has it been two weeks already..? I can't even remember what I've learned. 

OK. I've learned how to use Beer's law to determine the rate order of a reaction. I've also learned how to use experimentation with differing concentrations of crystal violent to determine the rate order when it reacts with OH ions. Sounds sophisticated, I know. On another note, I have also learned how extremely hard it is to become a Supreme Court Justice. 

I have recently completed both books for my English classes (finally) and about to complete the kinetics unit for his class. I have also (almost) conquered how to write a decent five paragraph essay in 40 minutes thanks to Comer. 

I plan on officially finishing up the kinetics unit with this take home test I am about to print out and take these last set of notes. I also plan on finishing up all the questions that go along with these lovely but long novels. And last but not least, focusing on our state competition! 

Friday Funfact:

Classification of Solids

The purpose of this lab was to identify the properties common to a particular class of solid, classify a solid substance by its propoerties, and to develop lab techniques to check the melting point, conductivity, solubility, and observe the gross properties of a solid substance.

We used our knowledge of chemical bonding to understand how the intermolecular forces within a solid affect its properties. With our results then, we were able to classify different solids into different categories.

We started by obtaining samples of MgO, CoCl2 * 6H20, phenyol saline acid, benzoic acid, charcoal, sand, iron and zinc into plastic well plates. We observed and recorded the crystals present in each of the samples. Then we tested the melting point by putting a small sample of each substance into test tubes and heating them with a Bunsen burner. We recorded the approximate melting point into a data table classified by less than 100 degrees, between 100 to 300 degrees, and greater than 300 degrees. Next, we tested the solubility. After organizing each substance into three small samples in two different well plates, we then obtained distilled water, ethanol, and cyclic acid (under the fume hood). We put about 20 drops of each liquid into the three samples of each substance and recorded if "all," "some," or "none" of the solid dissolved in the liquid. If all of the solid dissolved in the water, we tested its conductivity. Only the cobalt chlorine and potassium bromide were positive in conductivity.

Classification:

Molecular Solid                    Ionic Solid                   Metal                       Network Solid

Phenyl Saline                          MgO                            iron                            charcoal

benzoic acid                            CoCl2                         zinc                               sand

                                               KBr

Questions:

1. A) ionic solids

    B) (skipped)

   C) molecular solids

   D) metals

   E) molecular solids

2. This solid would be classified as a molecular solid because it has a very low melting point and has slight (not complete) conductivity. 

3. This solid would be classified as a network solid because it was a very high melting point, it is insoluble in all solvents, and does not conduct electricity. 

4. A) K- metal 

    B) CaCo3- ionic solid

    C) C8H18- molecular solid

    D) HCl- ionic solid

5. A) Network solids are generally insoluable in water

    B) Metals are generally ductile and malleable. 

    C) Ionic solids are generally nonvolatile. 

6. The melting point test did not seem to work too well because we could not precisely determine the temperature in which a substance started to melt. Also the solubility test because the cyclic acid reacted with the plastic well plates. 

Friday. 2/14/14

(Happy Valentine's Day)

So, I guess the most exciting thing I have learned these past couple of weeks was how to synthesize aspirin. Not to brag or anything but my sample was 47% pure...maybe I should look into the drug business. I have also learned that cyclic acid does not smell good and does not mix well with plastic.

Recently I have completed TWO labs in this class and am almost finished with the TWO books I am reading for English. Not to mention the President section in government class. Typical senior responsibilities I suppose.

Coming up, I plan to get through this next unit in chemistry without dying or being physically damaged with chemicals. I also plan on finishing up these two books within the next week or two. This upcoming week in competition week...so I plan on trying to survive through exhaustion (with the help of Starbucks, of course) and winning the competition this weekend at NMSU!

Pepper. Soap. Water.

Who knew three simple things could be so fun? Oh the wonders of chemistry.

Intermoluecular forces are defined as the bonds between two molecules and intramolecular forces are the bonds between atoms within one molecule. The intermolecular forces in water include dispersion, hydrogen bonding and dipole. While soaps seem to have weak van der waals forces.

(Water molecule diagram)

Here, with the soap and water alone, the soap did not dissolve. It seemed to have sink straight to the bottom and stay there. This can be explained by the polar and nonpolar ends of the soap molecules. The polar ends unnoticably dissolved at the surface of the water while the non polar ends sank to the bottom. This type of substance is known as a surfactant. The polar ends were strong enough to break the surface tension of the water. The surface tension of water is due to cohesion of the hydrogen bonding. Cool stuff.

 Now here is where the pepper was added to illustrate the interaction between the soap and water. The pepper stayed at the surface of the water. As I touched the surface with my soap covered finger, the pepper molecules seemed to "explode" and immediately spread to the edges of the cup. This visulization of repulsion is due to the intramolecular forces within the soap as well as the water. The intramolecular forces impact the intermolecular forces between the water and the soap. The polar ends of the soap molecules immediately repelled the polar forces from the hydogen bonds in the water.