Quantum Numbers

Last week, our chemistry class learned about quantum numbers. In the lecture, we were told that every atom is assigned a set of four quantum numbers. The first number is the principle quantum number. This number corresponds to the atom's principle energy level. The second number is the angular momentum quantum number. This digit represents the atom's final sublevel. The numbers are s=0,p=1,d=2,and f=3. Next, the third quantum number is the magnetic quantum number, which is determined on the last valence electron's placing on its orbital. This number can range from -3 to +3 when in a f sublevel. Finally, the last quantum number is the spin quantum number, which can either be -1/2 or +1/2. This is determined by knowing which direction the last valence electron in an atom faces (up or down on a chart). Below are examples:

http://chemwiki.ucdavis.edu/Core/Physical_Chemistry/Quantum_Mechanics/10%3A_Multi-electron_Atoms/Quantum_Numbers

Here are a couple links to help:

Purdue Information

Quiz

Study Links

While studying ahead for the quiz today, I found these links very helpful, further explaining electronic configurations:

Ground State v. Excited State

Box and Arrow Orbital Configurations

The Electronic Configurations of Atoms

Lab

Today in class, my partner and I conducted a lab using a spectrophotometer. To zero out the the machine, we used water in a cuvette and adjusted knobs to zero and one hundred percent transmittance. Then, we placed one of our solutions, Cr(NO3)3, also in a cuvette, in the machine to measure its percent transmittance and absorbance. Next, we placed the CoCl2 in a cuvette in the machine and measured its transmittance and absorbance. We repeated this entire process multiple times, changing the wavelengths each time. Here are some pictures from the lab below.

Flame Test

Today in class, we conducted the flame test. After passing a pre-lab that reviewed the lesson from yesterday, my partner and I went to the lab to start our experiment. We had various solutions and crystals, all of different metals. We took a wooden stick that soaked in the solutions and put it into a flame to see what color is produced. We also put crystals in the flame to see what color they made. With the color, we will be able to look at the light spectrum to find the metals wavelength. With this information, we will eventually be able to calculate the energy of one mole of photons for each various metal. Here are some pictures from the lab below:

New Unit

Today in class we learned the first lesson of our new unit, electronic structure. We discussed the wave nature of light and how every object has a wave nature. In addition, all waves have a characteristic wave length. Below is a picture of the different parts of a wavelength:

http://dev.physicslab.org/document.aspx?doctype=3&filename=wavessound_introductionwaves.xml

The longer the wavelength, the shorter the amplitude and the lower the energy. 

Next, we learned the formula for velocity. Here it is below, showing what each symbol means and the unit that corresponds with each:

http://accessiblemediacenter.techadapt.com/samples/CAST_Exemplars/Exemplar6/content/bodymatter-level2-121.htm

C, which is a constant (speed of light= 3.0x10^3) often replaces v in the formula. With at least two parts of the formula, we can solve for any of the pieces of the formula.

Here are a couple links that are helpful:
basic chemistry for mad scientist

ChemTeam

Percent Acetic Acid in Vinegar

For the last few days, my lab partner and I have been carrying out the percent acetic acid and vinegar lab, where we titrate acids in order to ultimately find the percent of acetic acid in commercial vinegar. First, we mixed about .5 grams of hydrogen phthalate into water to dilute it. Then, we added an indicator and titrated it with sodium hydroxide until the solution turned pink. When the solution turned pink, we knew that all of the KHP had been reacted with since the NaOH will react with the acid before the indicator. Next, we titrated diluted vinegar with the NaOH until it turned pink too (from the indicator). Since we recorded the amount of solutions used, we can calculate the molarity of the NaOH and find the molarity of the vinegar used. This information will eventually lead us into finding the vinegar's % of acetic acid in it. Here are some pictures from the lab:

Last Lesson

The last lesson that we learned about in the Acids and Bases unit involved stoichoimetry. Most questions asked to find the volume, pH, or concentration of a solution and gave about three pieces of information. For a couple of them, we had to find the limiting reagent. Here is a link to practice these types of question:

Chemteam


We also briefly discussed pH titration curves. Here is a picture comparing the titration curves of a strong acid and base:

http://chemistry.tutorvista.com/inorganic-chemistry/calculating-molarity.html

ICE Problems

To complete all of the questions from this lesson, we used the flow chart below.

http://www.sciencegeek.net/Chemistry/taters/Unit8pH.htm

In the chart, the OH- is the hydroxide ions and the H+ is the hydronium ions in a solution. By knowing one of the components on the chart, you can solve the pH, pOH, or the ions of the acids and bases in that particular solution.

An example of a problem that would utilize this chart looks like this. The question regularly involves finding the equilibrium:

http://pinl.net/vs/ice-tables-for-equilibrium.xhtml

In this problem, the I stands for INITIAL, which is the original information you are given. The C stand for CHANGE, which is +x, -x, -x most of the time across. Lastly the E is for EQUILIBRIUM. Once you place all of the components in the chart, you add them down. Next, you take those components and put them in the expression on the right, placing the products over the reactants in the solution (not including water) and equal that to the constant. Then, you distrubute the the costant to the fraction to come up with a quadratic formula. Next, with the formula, you place the parts of the formula to form a quadratic equation to find x. After you solve for x, you have the ion concentrations of either the acid or base you were looking for. Finally, if you wanted to find the pH or the pOH of the solution, you place the concentration in the antilog.

Here is a link to practice these types of questions and further explanations:
Explanation
Practice

The Strength of Acids and Bases

On Thursday last week, we learned how to tell if an acid and base reaction forms an acidic, basic, or neutral salt. In addition, we discovered how tell if a solution is acidic,basic, or neutral.

First, we discussed salts. Below is a chart that shows how to know if the salt formed is acidic, basic, or neutral. As long as you know if the acid and base mixed in the reaction is strong or weak, you can determine the property of the salt.

http://slideplayer.com/slide/2406970/

Next, we learned about the concentrations of hydroxide and hydronium ions in solutions. To find the concentrations, we manipulate the formula below to solve for the component that we want.

http://study.com/academy/lesson/the-ph-scale-calculating-the-ph-or-poh-of-a-solution.html

You are usually given one of the concentrations and know that kw= 1.0 x 10^-14. So with those two pieces of information, you can find the solution's other concentration.

Here are a couple links that you can practice with and quiz yourself on with answers:
Predicting Salt pH
Calculating H-OH Ion Concentrations