Tuesday, January 11, 2011
Tues-Day 2
Physics - took part 1 of the Electrostatics unit exam.
AP Chem - launched the Kinetics unit by discussing the THREE possible factors that determine the number of effective collisions per second i.e. the reaction rate.
We then explained how chemical reaction rates have a range that is set by the nature of the reactants.
After that, we discussed FOUR factors that can be varied in a gien reaction: concentration, temperature, surface area, and the addition or removal of a catalyst.
We explained how each factor affected the three primary determinants of the reaction rate: kinetic energy/force of collisions, orientation of collisions, and collision frequency.
We then discussed how reaction rates are measured in terms of change in MOLARITY per second; this unit is practical because a sample of the reacting mixture can be removed without changing the concentrations of reactants and products at the time of sampling. (However, there is NOTHING wrong or illogical about stating a reaction rate in terms of change in the number of moles or molecules per second!)
We saw how to measure the average rate of reaction, and the instantaneous initial rate of reaction, which is the typical standard for measuring reaction rates.
We discussed how to get a single "rate of reaction", whether we are measuring the rate of disappearance of a reactant, or rate of appearance of a product. We simply divide the rate of appearance or disappearance by the coefficient of the respective product or reactant from the BALANCED chemical equation.
AP Chem - launched the Kinetics unit by discussing the THREE possible factors that determine the number of effective collisions per second i.e. the reaction rate.
We then explained how chemical reaction rates have a range that is set by the nature of the reactants.
After that, we discussed FOUR factors that can be varied in a gien reaction: concentration, temperature, surface area, and the addition or removal of a catalyst.
We explained how each factor affected the three primary determinants of the reaction rate: kinetic energy/force of collisions, orientation of collisions, and collision frequency.
We then discussed how reaction rates are measured in terms of change in MOLARITY per second; this unit is practical because a sample of the reacting mixture can be removed without changing the concentrations of reactants and products at the time of sampling. (However, there is NOTHING wrong or illogical about stating a reaction rate in terms of change in the number of moles or molecules per second!)
We saw how to measure the average rate of reaction, and the instantaneous initial rate of reaction, which is the typical standard for measuring reaction rates.
We discussed how to get a single "rate of reaction", whether we are measuring the rate of disappearance of a reactant, or rate of appearance of a product. We simply divide the rate of appearance or disappearance by the coefficient of the respective product or reactant from the BALANCED chemical equation.
# posted by C @ 11:01 PM 
