Friday, January 20, 2012
Fri-Day 1
AP Chem - we showed the "steady-state" approximation method i.e. when a proposed reaction mechanism does add up to the net equation but does not have a single elementary step that agrees with the experimental rate law; in this case, you can label the first step "fast", which reaches equilibrium between its forward and reverse steps (use a double arrow) and has a product or products that are used in the next "slow" or rate determining step. We saw that, by equating the forward and reverse reaction rate laws of the first step, that an algebraic "substitution" is possible for one of the "intermediate" molecules in the rate-determining step, which may yield agreement with the experimental rate law.
This may work, but does not HAVE to work. You must at least try the substitution, especially when you see a fast step followed by a slow step in a mechanism that does not obviously initially agree with the experimental rate law.
We explained why there is no substitution for a slow then fast step mechanism.
We then went on to experimental rate data table analysis in which we can determine the experimental rate law from three or more controlled experiment involving changing reactant concentrations, usually one reactant at a time.
We will do the formal method on Monday.
Bio - we focused on the heartbeat cycle, showing the flow of blood to and from the various parts of the heart and the important vessels directly leading to and from the heart. We discussed the heart valves, their names and functions.
We also discussed the meaning and cause of the systolic and diastolic blood pressure measurements.
This may work, but does not HAVE to work. You must at least try the substitution, especially when you see a fast step followed by a slow step in a mechanism that does not obviously initially agree with the experimental rate law.
We explained why there is no substitution for a slow then fast step mechanism.
We then went on to experimental rate data table analysis in which we can determine the experimental rate law from three or more controlled experiment involving changing reactant concentrations, usually one reactant at a time.
We will do the formal method on Monday.
Bio - we focused on the heartbeat cycle, showing the flow of blood to and from the various parts of the heart and the important vessels directly leading to and from the heart. We discussed the heart valves, their names and functions.
We also discussed the meaning and cause of the systolic and diastolic blood pressure measurements.
# posted by C @ 7:31 PM 
