Thursday, December 18, 2008
Thurs-Day 2
AP Chem- we discussed the strengths of bonds in terms of "average" bond enthalpies also known as "bond dissociation energies". We can use these values to estimate the change in enthalpy for a reaction between gaseous molecules.
We're not going to use any fancy formula for these problems; in THIS case, formulas lead to wrong algebraic signs and faulty calculation. We'll go this simple visual route by drawing out any and all reactant bonds that are broken (REQUIRING ENERGY (+)) and the draw out all product bonds that form (RELEASING ENERGY (-)). Just add up the values and you have the change in enthalpy for the reaction!
Note: do NOT count a double bond as two "single" bonds. Bond energies do NOT work that way obviously because sigma and pi bonds require DIFFERENT amounts of energy to break.
DO as many problems as possible for tomorrow's exam. That is really the only way to prepare for exams in general in this course. Fortunately, there are lots of problems to practice with and with which you can check your answers!
Bio 6- we introduced the unit on nutrition/the digestive system by going step-by-step through a video to look at the various structures and functions involved in the digestive system; this system is essential for you to break down the complex molecules in food so that they can be absorbed (mostly via diffusion) into your body's cells.
Bio 7/8 -we introduced the unit on nutrition/the digestive system by going step-by-step through a video to look at the various structures and functions involved in the digestive system; this system is essential for you to break down the complex molecules in food so that they can be absorbed (mostly via diffusion) into your body's cells.
We then did a simulated perspiration lab to see the faster cooling effect caused by sweating.
We're not going to use any fancy formula for these problems; in THIS case, formulas lead to wrong algebraic signs and faulty calculation. We'll go this simple visual route by drawing out any and all reactant bonds that are broken (REQUIRING ENERGY (+)) and the draw out all product bonds that form (RELEASING ENERGY (-)). Just add up the values and you have the change in enthalpy for the reaction!
Note: do NOT count a double bond as two "single" bonds. Bond energies do NOT work that way obviously because sigma and pi bonds require DIFFERENT amounts of energy to break.
DO as many problems as possible for tomorrow's exam. That is really the only way to prepare for exams in general in this course. Fortunately, there are lots of problems to practice with and with which you can check your answers!
Bio 6- we introduced the unit on nutrition/the digestive system by going step-by-step through a video to look at the various structures and functions involved in the digestive system; this system is essential for you to break down the complex molecules in food so that they can be absorbed (mostly via diffusion) into your body's cells.
Bio 7/8 -we introduced the unit on nutrition/the digestive system by going step-by-step through a video to look at the various structures and functions involved in the digestive system; this system is essential for you to break down the complex molecules in food so that they can be absorbed (mostly via diffusion) into your body's cells.
We then did a simulated perspiration lab to see the faster cooling effect caused by sweating.
# posted by C @ 4:41 PM 
