Monday, November 3, 2008
Mon-Day 1
AP Chem- Here is the Unit 5 Gases HW: text pages 187-230, do the following problems to be handed in next week (will post the exact date later):
32, 46, 52, 68, 74, 80, 82, 85, 108, 112
We applied the "density to molar mass" version of the ideal gas law in which we are given either grams of gas, volume, temperature, and pressure to determine the gas's molar mass or we are given a known gas (or its molecular formula), its mass, temperature, and pressure to determine its density under those SPECIFIC conditions (remember that the density of a gas varies with temperature and pressure).
We then derived Dalton's Laws of Partial Pressure, which are fairly obvious, if you draw a picture of gas molecules in a container and understand that the molecular collisions with the container and each other cause the pressure. We saw that the NUMBER of molecules (or MOLES of molecules) of a given gas determines that gas's contribution to the total pressure; we also noted that the sum of all of the gases' partial pressures must equal the total pressure due to the gases in the container (which sounds quite circular in reasoning!).
The partial pressure of a given gas equals its MOLE FRACTION times the total gas pressure in the container.
We then did a gas stoichiometry problem (just like any other stoichiometry problem, really) that looked a bit different due to the bulb apparatus that keeps the gaseous reactants initially separate. In these problems, you do have to take into account that the entire container volume is used once the valve is opened to let the gases mix and/or react!
We saw that this was a typical limiting reactant problem in which we determined all mole quantities by using the ideal gas law. We then used Dalton's Laws to get the partial pressure of each remaining gas.
Finally, we started/continued our ultimately long practice with descriptive chemistry by discussing the four KEY gas-forming reactions.
Bio 6/7- took the Mitosis, DNA, Asexual Reproduction exam. Then we finished the data collection on the Mitosis Lab and the Osmosis in the Onion Cell Lab.
Grading the test, I noticed that many of you made careless errors by NOT identifying/underlining/circling key terms in the question and using those terms in your answer; to avoid losing points needlessly in the future, do not forget this when you see your easily avoidable errors on your test papers.
Overall, the class average was high though (but it could have been even higher).
Bio 8- took the Mitosis, DNA, Asexual Reproduction exam. Grading the test, I noticed that many of you made careless errors by NOT identifying/underlining/circling key terms in the question and using those terms in your answer; to avoid losing points needlessly in the future, do not forget this when you see your easily avoidable errors on your test papers.
Overall, the class average was high though (but it could have been even higher).
32, 46, 52, 68, 74, 80, 82, 85, 108, 112
We applied the "density to molar mass" version of the ideal gas law in which we are given either grams of gas, volume, temperature, and pressure to determine the gas's molar mass or we are given a known gas (or its molecular formula), its mass, temperature, and pressure to determine its density under those SPECIFIC conditions (remember that the density of a gas varies with temperature and pressure).
We then derived Dalton's Laws of Partial Pressure, which are fairly obvious, if you draw a picture of gas molecules in a container and understand that the molecular collisions with the container and each other cause the pressure. We saw that the NUMBER of molecules (or MOLES of molecules) of a given gas determines that gas's contribution to the total pressure; we also noted that the sum of all of the gases' partial pressures must equal the total pressure due to the gases in the container (which sounds quite circular in reasoning!).
The partial pressure of a given gas equals its MOLE FRACTION times the total gas pressure in the container.
We then did a gas stoichiometry problem (just like any other stoichiometry problem, really) that looked a bit different due to the bulb apparatus that keeps the gaseous reactants initially separate. In these problems, you do have to take into account that the entire container volume is used once the valve is opened to let the gases mix and/or react!
We saw that this was a typical limiting reactant problem in which we determined all mole quantities by using the ideal gas law. We then used Dalton's Laws to get the partial pressure of each remaining gas.
Finally, we started/continued our ultimately long practice with descriptive chemistry by discussing the four KEY gas-forming reactions.
Bio 6/7- took the Mitosis, DNA, Asexual Reproduction exam. Then we finished the data collection on the Mitosis Lab and the Osmosis in the Onion Cell Lab.
Grading the test, I noticed that many of you made careless errors by NOT identifying/underlining/circling key terms in the question and using those terms in your answer; to avoid losing points needlessly in the future, do not forget this when you see your easily avoidable errors on your test papers.
Overall, the class average was high though (but it could have been even higher).
Bio 8- took the Mitosis, DNA, Asexual Reproduction exam. Grading the test, I noticed that many of you made careless errors by NOT identifying/underlining/circling key terms in the question and using those terms in your answer; to avoid losing points needlessly in the future, do not forget this when you see your easily avoidable errors on your test papers.
Overall, the class average was high though (but it could have been even higher).
# posted by C @ 8:26 AM 
