video: The World of Chemistry: The Atom click the VOD button by #6-The Atom. 28 minutes. A review of the atom that summarizes this week's lesson aims, particularly in the last 10 minutes. If you are very comfortable with the whole atomic theory stuff, just watch the last 10 minutes and go on to the more advanced material from The Mechanical Universe: Particles and Waves click the VOD button for #50. This is extra understanding for those of you who wish to go deeper. 28 minutes. and fascinating (to me). If you are intimidated by the math, just pretend that the equations are doing complicated dance moves. If this year has been your first introduction to atomic theory, just watch the first video in its entirety and skip the second.
Textbook reading: 11.7-11.8 which may make our whirlwind tissue paper art project have a little more meaning to us. Answer end of chapter questions for each section.
Lastly, a site to peruse: The Orbitron Don't read it, just click on the various sub-levels to see the increasing complexity of the higher energy levels.
Thank you for your very excellent work on the lab reports, and for the fantastic level of cooperative learning demonstrated in class. You make me feel like a real teacher.
also explore these simulations (PLEASE MAKE THIS WORK: IF YOU HAVE DIFFICULTIES WITH THE COMPUTER, PROBLEM SOLVE IT/GET HELP- DON'T JUST SKIP IT.) None of these sims have directions, so it is up to you to explore enough to figure out what it's all about.
By now I have most certainly crossed the line into too-much homework. The bright side (no pun intended) is that if you did not understand the quantum weirdness, no one expects you to ! Let me know if you need help with the math on Thursday; we can go over the worksheet in class.
There are, of course, lots of interesting videos that you can find on youtube.
Thursday, February 13, 2014
Homework...do this on Friday if you can, to finish up your lab reports, along with calculations for your top two candidates -- SHOW WORK NEATLY!\
And as a summation, and if you have not already done so, watch these videos from Mr. Anderson : http://www.bozemanscience.com/ap-chemistry/ TAKE NOTES AS YOU WATCH, TO BE PREPARED FOR A TEST NEXT MONTH.---this will actually save you time.
First, read this handout from The Joy of Chemistry:When Matters Heat Up(10 pages) ...and finally... Work on your lab reports, first draft due on Thursday. Communicate with your team to divide up the work, and be super-super diligent to include all the information you are asked for, do all the calculations, show all the work, discuss all the points and questions. Re-read the handout with highlighter in hand, and underline every little bit that you must be sure to include in the report. Check last homework blog for directions on the format of a lab report. (Also, I did give you a handout at the beginning of the school year; it should still be in your binder.) *To compare materials safety, google MSDS calcium chloride, etc. You may also wish to know how much a packet of handwarmer usually costs, at a ski slope in Tahoe, for example. Good job in class; you are the dream team of chemistry.
Friday, February 7, 2014
Read the Cartoon Chemistry handout from class.
MAIN THING: Go over the Handwarmer experiment pages, preparing for the actual experiment on Monday. If you'd like a new copy: Handwarmer HandoutIt would be really helpful to make a data table-) Anyway, read and re-read, really carefully. This is an inquiry lab, so the procedure you follow at this point is up to your team, but you will have to write down that procedure in a lab report. WE WILL DO AN ACTUAL LAB REPORT ON THIS EXPERIMENT! lab report guidelines
To practice figuring out the molar heat of solution, work the odd numbered problems on the Enthalpy Calorimetry worksheet 16-4 AGAIN! (which you did last homework period) but add in the final step of calculating the molar heat of solution. ANSWERS My math steps here are much clearer than they were in class.worksheet 16-4 again
Lastly, there are some splendid videos from Mr. Anderson on this page. http://www.bozemanscience.com/ap-chemistry/
Big Idea # 5 - Thermodynamics, videos 46-53 Each video is about 8 minutes, so start watching as you have time-- not all at once --finish up next week. Take notes.
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In Summary
:
During a chemical reaction, energy is needed to break the bonds between atoms. As new
bonds form, energy is produced. The difference between the energy required and the energy produced is called the heat of reaction. heat change heat change heat change That energy difference is usually manifested in a temperature change.
If, as is the usual case, more energy is produced than is required, the excess energy is
given off as heat. This heat causes the temperature of the chemicals, container, and
surroundings to increase. A reaction of this type is called exothermic.
There are some reactions that will proceed even though more energy is required than is
produced. This type of reaction is called endothermic and is characterized by a decrease
in the temperature of the chemicals, container, and surroundings.
Chemists measure the heat of reactions with calorimeters. The energy, as heat, is
absorbed by water in the calorimeter. The difference in the temperature of the water before and after the reaction is used to calculate the heat of reaction. The calorimeter is
insulated to prevent heat exchange with the surroundings. The heat of the reaction is then
equal to the heat absorbed by water and the calorimeter.
Yesterday we attempted to determine how much heat went into our calorimeters. Since we got such divergent results, perhaps we should check our math. I did the lab in my kitchen and got a specific heat of the calorimeter of 63 J/degree Celcius. Here is my data table:
Tinitial/cold = 13 degrees C
Thot = 66 degrees C
Tave = 39.5 degrees C
Tmix = 37.5 degrees C
qwater = (200g)(4.184)(37.5-39.5 C) = - 1673 joules
q water = - q cal ("The heat gained by the calorimeter is equal to that lost by the water, but opposite in sign.")
q cal = 1673
C cal = 1673 / 39.5 -13 = 63 J/ Celsius)
q is "energy transferred as heat" and you might remember q as the quantity of heat, since it is measured in joules.
Are there other sources of error, perhaps? Did the thermometer finish rising/falling, or perhaps too much heat was lost because we did not use a lid? Any other ideas?
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So here's more math - Enthalpy Stoichiometry - and here's a teacher explaining: (the first 8 minutes will help you on this worksheet, so after 8 minutes please stop the video and do the worksheet >>answers at the end of the blog. Correct me if I'm wrong.) Also, watch with pencil and paper in hand, and do the math along with the teacher.
Finish watching the video, and then work on this worksheet Enthalpy Calorimetry, problems 1,3,5 only. All these problems assume no heat is lost to the calorimeter, so the simple equation to use is q=mcAT (I think) also remembering that deltaH=-q (sorry, the blog has no Greek letters to use, that I know about)
(you may notice a discrepance in the signs of delta H)
