Intermolecular Forces January 28, 2008
Helpful websites:
Georgia Southern’s website with pictures from class and other tutorials for VSEPR and polarity (good for quest review)
AP Chem Chapter 5 Test - Gas Laws January 17, 2008
Basically, you want to know how the properties of gases affect each other, what makes gases special from other phases of matter, the differences of the ideal gases and real gases, how to use ALL your equations and what the variables stand for (the appropriate R values for each), how to convert from one unit to another, whenever you used temp. it should be in Kelvins, gas law stoichiometry, mole fraction and partial pressures, the postulates of the KMT, diffusion and effusion. You will be given equations and constants.
Very not related to class… January 10, 2008
So as most of my students know, I am going to have a baby, supposedly in May. If you would like to have some fun, you can visit expectnet.com and participate in our little prediction game. For the game name so you can log in, just ask me at school or send me an email.
Significant Digits Reminder January 10, 2008
Remember that significant digits are important because they help to reflect the precision of the instruments used to make the measurements involved in a calculation. I have posted about this before with some websites you can use to help you practice. The second website is actually quite good and has a lot of practice for you to try. The third website, I think, has been removed but the other two are fine. If you have any questions after doing these tutorials, please feel free to comment, even if you are not one of my students!
AP Chemistry Chapter 5 help January 1, 2008
If you are working on your Chapter 5 Independent Study, please post questions to this topic. Kylee asked the following:
I started on the problems and i understand the pressure stuff in the first section but i don’t understand the unit stuff for problems 27 and 29. Its the exact same type of problem so i’m guessing i kinda need to know what I’m doing. I know the equation to use is P(gas)=P(atm) +( or -) h. But since h is in m or cm and P(atm) is in (atm, torr, Pa, etc.) how do you do that?
One thing that will help you is that the unit of Torr is the same as millimeters of mercury, noted as mm Hg. On the weather reports on TV, they report this in inches of mercury because the average Americans a) don’t know what a millimeter is and b) don’t much care what the atmospheric pressure is. Anyways, mm Hg is the same as a Torr so when 1 atm equals 760 Torr, this is also 1 atm = 760 mm Hg. If your height is given in meters or centimeters, just use your metric conversion expertise and move the decimal. Also, a few other tips:
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Pay attention to if the manometer is closed or open ended. Closed-end manometers don’t have anything to do with atmospheric pressure and the pressure of the gas is equal to the height difference of the mercury. For open-ended manometers, if the gas pressure is more than atmospheric, then the mercury will be higher on the atmosphere side so the height difference must be added to the atmospheric pressure. If the gas pressure is less than atmospheric, the atmosphere will push more on the mercury and the mercury will be higher on the gas side. This height must be subtracted from the atmospheric pressure.
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More posted as I receive more questions…
Good luck! I hope you are all having a great break and are enjoying the snow!
