Wednesday, March 11, 2009
Wednes-Day 1
AP Chem- we derived the Henderson-Hasselbalch equation and saw that it is really just a rearranged version of what we have always done: Ka expression filled with the values from the ICE table.
The "easy" part is that, in the H-H form, we can ignore the insignificant amount of hydrolysis that occurs when the parts of a buffer are mixed AS LONG AS THE CONJUGATE ACID TO BASE RATIO IS WITHIN the 1:10 or 10:1 RANGE!
We did a sample buffer problem and saw that:
1. the pH = pKa when the conjugates are at equal concentrations
2. the pH will go up a bit or down a bit depending on which conjugate is in greater concentration.
We then derived the base version of the H-H equation and made a basic buffer solution and calculated the conjugate concentrations, pH, etc.
We tried a couple of problems in which the final concentrations of the conjugates are not given; that is, we mixed two SEPARATE solutions of the conjugates that, when mixed, DILUTE their initial concentrations. Once we calculate the final concentrations (thanks to the MILLIMOLE), we plug those values into the H-H equation (if within buffer range, otherwise you must use an ICE table!) and solve for the buffer pH.
Lastly, we began to discuss acid-base titrations (there are four combinations of which we will discuss three). We started by looking at a characteristic strong-strong acid-base titration curve (profile).
Bio 6/7- we reviewed, with a comprehensive graph and picture, step-by step, the stages and hormonal regulation of the menstrual cycle.
We then did a manipulation lab in which we sequenced and noted the changes in the various stages of the menstrual cycle.
Bio 8- we reviewed, with a comprehensive graph and picture, step-by step, the stages and hormonal regulation of the menstrual cycle.
The "easy" part is that, in the H-H form, we can ignore the insignificant amount of hydrolysis that occurs when the parts of a buffer are mixed AS LONG AS THE CONJUGATE ACID TO BASE RATIO IS WITHIN the 1:10 or 10:1 RANGE!
We did a sample buffer problem and saw that:
1. the pH = pKa when the conjugates are at equal concentrations
2. the pH will go up a bit or down a bit depending on which conjugate is in greater concentration.
We then derived the base version of the H-H equation and made a basic buffer solution and calculated the conjugate concentrations, pH, etc.
We tried a couple of problems in which the final concentrations of the conjugates are not given; that is, we mixed two SEPARATE solutions of the conjugates that, when mixed, DILUTE their initial concentrations. Once we calculate the final concentrations (thanks to the MILLIMOLE), we plug those values into the H-H equation (if within buffer range, otherwise you must use an ICE table!) and solve for the buffer pH.
Lastly, we began to discuss acid-base titrations (there are four combinations of which we will discuss three). We started by looking at a characteristic strong-strong acid-base titration curve (profile).
Bio 6/7- we reviewed, with a comprehensive graph and picture, step-by step, the stages and hormonal regulation of the menstrual cycle.
We then did a manipulation lab in which we sequenced and noted the changes in the various stages of the menstrual cycle.
Bio 8- we reviewed, with a comprehensive graph and picture, step-by step, the stages and hormonal regulation of the menstrual cycle.
# posted by C @ 1:52 PM 
