Unit Test

Friday's test went pretty well, I do say. It may have been a little more difficult than the quiz as I was a bit uneasy on a couple questions. Some questions asked about acidity and alkalinity, which I didn't really know how to answer, so I guessed on those. This test was much easier than past tests and I feel rather well about this one.

Periodic Trends Lecture

The final installment of the electronic structure unit is periodic trends. The periodic table follows a couple of trends that can provide details about various atoms (only S and P block atoms though). The different trends were a bit hard to differentiate and remember what each one specifies, but I think with some more studying, they will be easily remembered. I'm feeling pretty good about the test on Friday, but I still definitely need to look over this lecture, which I believe may be the hardest lesson of the unit (but still not that difficult).

https://en.wikipedia.org/wiki/Periodic_trends

Helpful link:https://www.youtube.com/watch?v=XK-WTYncldA

Weekly Quiz

We took this unit's weekly quiz. Much of the quiz came directly from the online practice which I use to study. It wasn't as difficult as some of the other units.

Here are some links for future studying: 

http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch6/relativeenergypractice.html

http://www.rsc.org/learn-chemistry/wiki/Quiz:GeneralI001:_Electron_configuration
https://www.youtube.com/watch?v=I58ByiqnXcY

Spectroscopic Analysis Lab

We performed yet another lab. This lab was not nearly as exciting as the flame test lab. For this lab, we adjusted various knobs on a spectrophotometer and found the amount of light in blue and pink solutions. It was really difficult to adjust the knob so that the number read exactly what it was supposed to. This was extremely time-consuming as we had to re-adjust the knobs for every single different wavelength. Additionally, it was dull as all the lab consisted of was a) adjust the knobs and b) record the number.

Lecture on Electronic Structure

We've started a new unit, and it has been going pretty well. At first, the unit seemed a bit confusing, but it all began to make sense gradually. The first lesson of the unit was on wavelengths of light. We learned the formula for the speed of light (C= frequency x wavelength) and for energy (E= Planck's constant x frequency). These two formulas were easy to understand as problems associated with the lesson are pretty basic plug-and-chug. Yesterday, we learned about the electron configuration of elements. This lesson was chockful of vocab and steps to memorize. It was definitely a bit confusing and time-consuming at first to figure out each element's different electron structure and diagram and to memorize all the little rules for different types of elements. However, I soon began to understand it, and I even think it's a bit fun (Something I have NEVER said about chemistry, so that's saying a lot!). 

http://chemwiki.ucdavis.edu/Core/Inorganic_Chemistry/Electronic_Structure_of_Atoms_and_Molecules/Electronic_Configurations

Some links for review on these lessons:

http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch6/electronconfigpractice.html
http://www.sciencegeek.net/Chemistry/taters/Unit2ElectronNotations.htm
https://www.youtube.com/watch?v=2AFPfg0Como

Flame Lab

Today in class we had another lab, one which may be my favorite lab we've done all year: the Flame Test Lab. Basically, we placed several different chemical compounds and solutions in the flame of a Bunsen burner to see the various colors each one produced. It was really awesome to see the vivid colors that varied among each metal. The smell was really reminiscent of summer (fireworks, bonfire, you get the picture) when we first walked in due to the Bunsen burners.

Useful Links

http://www.chemtutor.com/acid.htm#math


https://www.khanacademy.org/science/chemistry/acid-base-equilibrium/titrations/v/titration-calculation-example

http://www.sparknotes.com/testprep/books/sat2/chemistry/chapter6section6.rhtml

http://www.chem.wisc.edu/deptfiles/genchem/sstutorial/Text12/Tx121/tx121.html

Unit Test Reflection

I have heard people say the acid base unit test is the most difficult test of the year. Those people were exactly right that was by far the most difficult test we have taken all year. 10/10 most difficult test. I barely knew what I was doing on that thing.

Unknown Acid Lab

This week, we've been working on another titration lab that is pretty much identical to last week's Acetic Acid lab. The only thing that's changed is that we're not using acetic acid, but an unknown acid. We still titrated the unknown acid with NaOH, just like the acetic acid lab. Another thing that's been added to this lab is that we have to heat the solution as the unknown acid does not dissolve as easily as acetic acid. It's pretty neat seeing the solution turn into a mini tornado when the magnet is added to the flask and spins due to the magnet in the heater.

Titration Lab

We've been working on a new lab. The purpose of the lab is to standardize a solution of NaOH with KHP, and then, use that solution's molarity to determine the percentage of acetic acid is in vinegar. To start, we filled the buret with NaOH, and measured out some KHP on a weigh boat. We transfered the KHP to a flask, and filled it with water to make a solution of 75 mL. Next, we added three drops of phenolphthalein to act as a color indicator for the endpoint. Lastly, we slowly drained the NaOH solution into the flask until the solution reached a permanent pink color. This was the hard part as we never knew exactly when to stop, but then again, we couldn't go too slowly as we needed to finish within a class period.

Acid-Base Quiz

We took our weekly quiz for the beginning of our Acid-Base unit. The quiz was "supposedly" difficult, but I thought it to be quite easy, as did many of my peers. It was such a great feeling calculating an answer actually listed as one of the choices! The quiz was mostly math, with a few definition questions. The math was primarily pH calculations, which is fairly easy, except when dealing with weak acids/bases, which require the "ICE box" method.

http://www.sciencegeek.net/APchemistry/APtaters/pHcalculations.htm

First Acid-Base Lecture

We started our new unit on acids & bases. So far, the majority of the lessons are not very complex nor difficult to understand. I may just need to study some of the vocab again. The lecture consisted of identifying the differences between acids and bases, strong vs. weak, and Arrhenius vs Bronsted-Lowry acids. This was probably the most difficult out of the two lectures we've had so far as it was very vocab-packed, and there are some rules that need to be memorized in order to identify what type of acid or base a substance is. Today's lecture was more math based in that we had. It was basic math and involved a simple formula to find the M of either H or OH ions in a reaction.

Vitamin C Lab

We did the Vitamin C lab. My pre lab question was a math one, and it really wasn't hard at all. You just needed to know the formula of calculating concentration by dividing the drops of iodine needed to reach the endpoint of the sample over the drops of iodine needed to reach the endpoint of the standard. The actual lab consisted of measuring the number of drops of iodine were needed to reach the endpoint (when the solution turned permanently blue) of various fruit juices: pear, apple, grapefruit, v8. We then compared these numbers to the number of drops needed to reach the endpoint of a standard Vitamin C solution, made by a dissolved 500mg Vitamin C tablet in 500mL of water. We performed 3 trials while everyone else mostly performed 2 trials. This was to make sure we were being extra accurate, but when we actually looked back at our data for the trials, it seemed as if that extra trial just threw the average off. For example, the standard solution had endpoints of 39, then 27, and finally in the 3rd trial, it had an endpoint of 55. So, it totally threw off the average of the endpoint of the solution. This was probably due to the fact that we did the third trial on the second day of lab, when we had a new standard made. The standard was most likely much different than the standard from day one, throwing our number off.

Finally, we compared the numbers to figure out which juice had the highest concentration. The more drops of endpoint, the higher the concentration that solution would have. The lineup from most concentrated to least was Vitamin C standard, apple juice, v8 Golden Goodness, and finally, pear nectar.

Helpful links

https://www.youtube.com/watch?v=KVZ_KS45rVg

http://chemcollective.org/activities/tutorials/stoich/solution_stoi

https://chemistry11mrstandring.wikispaces.com/Stoichiometry+Calculations+Involving+Molar+Concentration

http://www.quansysbio.com/dilutions

https://www.youtube.com/watch?v=rPND65LPwS0&feature=youtu.be

http://www.chemteam.info/Solutions/Molarity.html

Molarity in Stoichiometry

Our final lecture of the unit aqueous solutions was how to tie molarity to our stoichometry calculations we have learned in previous units. We learned how to find grams, volume, moles, or molarity of a substance, using molarity (mol per 1L) as a conversion factor. We can use molarity to get from volume to moles, and then subsequently from moles to grams, and vice versa.

http://employees.csbsju.edu/hjakubowski/classes/Chem%20and%20Society/stoichiometry/olstoichiometry.htm