Thursday, October 16, 2008
Thurs-Day 1
AP Chem- we solved the conundrum from yesterday's combustion analysis problem; why did our empirical formula have crazy numbers? Because the total mass of carbon and hydrogen (from the carbon dioxide and water, respectively) did not add up to the mass of the original unknown compound i.e. the law of conservation of mass was not observed. That told us that there MUST be another element in the original compound; that compound must be oxygen because that is the only other element in the products!
We then solved, by subtraction, for the mass of O in the unknown, converted to moles, got the simplest whole number mole ratios, which led us to the empirical formula of para-cresol: C7H8O.
We used the molecular mass to get the scaling factor, with which we determined the molecular formula. The scaling factor was an INTEGER so we knew that the empirical formula was correct.
We then discussed a bit of organic naming on benzene type rings: ortho, meta, para, with which we deduced the structural formula of the alcohol- no wonder that its an herbicide.
We re-started our hydrate lab during which we used the percent composition of prospective/possible hydrates of copper II sulfate in order to judge when the "constant mass" heating was likely over.
I'll return your exams tomorrow and we'll try to do a lot before this weekend so that you can make a big dent in the practice tests on Blackboard.
Bio 6/7- tomorrow we have our unit exam on Cells and forms of Cell Transport. There are lots of links, videos, practice sheets with answer keys for you to reinforce your knowledge.
Looking forward to an even more successful outcome on this unit; make sure that you use the test-taking skills that you have learned so far this year- they can ONLY help your score.
We finished our final cell objectives on cells, showing how and why they work together to maintain homeostasis in a cell to keep it alive.
We finished our plant and animal cell; for reinforcement, we added an activity in which we could see the results of osmosis when the plant cells are placed in a hypotonic and a hypertonic solution.
Bio 8- tomorrow we have our unit exam on Cells and forms of Cell Transport. There are lots of links, videos, practice sheets with answer keys for you to reinforce your knowledge.
Looking forward to an even more successful outcome on this unit; make sure that you use the test-taking skills that you have learned so far this year- they can ONLY help your score.
We finished our final cell objectives on cells, showing how and why they work together to maintain homeostasis in a cell to keep it alive.
We then solved, by subtraction, for the mass of O in the unknown, converted to moles, got the simplest whole number mole ratios, which led us to the empirical formula of para-cresol: C7H8O.
We used the molecular mass to get the scaling factor, with which we determined the molecular formula. The scaling factor was an INTEGER so we knew that the empirical formula was correct.
We then discussed a bit of organic naming on benzene type rings: ortho, meta, para, with which we deduced the structural formula of the alcohol- no wonder that its an herbicide.
We re-started our hydrate lab during which we used the percent composition of prospective/possible hydrates of copper II sulfate in order to judge when the "constant mass" heating was likely over.
I'll return your exams tomorrow and we'll try to do a lot before this weekend so that you can make a big dent in the practice tests on Blackboard.
Bio 6/7- tomorrow we have our unit exam on Cells and forms of Cell Transport. There are lots of links, videos, practice sheets with answer keys for you to reinforce your knowledge.
Looking forward to an even more successful outcome on this unit; make sure that you use the test-taking skills that you have learned so far this year- they can ONLY help your score.
We finished our final cell objectives on cells, showing how and why they work together to maintain homeostasis in a cell to keep it alive.
We finished our plant and animal cell; for reinforcement, we added an activity in which we could see the results of osmosis when the plant cells are placed in a hypotonic and a hypertonic solution.
Bio 8- tomorrow we have our unit exam on Cells and forms of Cell Transport. There are lots of links, videos, practice sheets with answer keys for you to reinforce your knowledge.
Looking forward to an even more successful outcome on this unit; make sure that you use the test-taking skills that you have learned so far this year- they can ONLY help your score.
We finished our final cell objectives on cells, showing how and why they work together to maintain homeostasis in a cell to keep it alive.
# posted by C @ 12:26 PM 
