Wednesday, March 18, 2009
Wednes-Day 2
AP Chem-study tips! During study and during the test tomorrow, help yourself out by DRAWING a beaker with any and all substances that are in solution! Start with any and all INITIAL quantities/substances and then SEPARATELY draw an "after" picture to see what is reacting (conjugate acid w/ base added or vice-versa or simple hydrolysis, etc.); THEN, write your ICE or SRFC table and see whether or not you can use simplifying assumptions or the H-H equation.
Truth in advertising:
your test tomorrow will have-
1. a polyprotic acid problem (as seen in the notes) in which all eq. quantities are solved for.
2. a FULL titration of either a weak acid or a weak base and calculations at the typical points of interest.
3. a buffer solution pH calculation before and after addition of a strong acid or base (exactly as done in the notes)
4. Lewis acid and base theory in words and Lewis structures.
5. Titration curves and selection of appropriate indicators.
6. Selecting the correct substances in order to make a buffer of a particular pH.
Be prepared and do well on this challenging exam because the next test is even more challenging for sure.
Finished the acid-base unit by discussing the polyprotic acid titration curve and noting the various buffer regions. We also saw how buffers of a particular pH can be made by choosing suitable combinations of salts of the conjugate amphoteric bases of the polyprotic acid.
Depending on the desired pH, you should choose a salt that has an acidic (even though the ion is amphoteric, just consider it acting as an acid in this case) ion that has a pKa near the desired pH along with a salt that contains the conjugate base of that acidic ion.
We then began the ultimate challenge (as you quickly saw, perhaps?) of our course: sparingly soluble salt equilibria (NOT on tomorrow's exam).
We introduced this topic by painstakingly pointing out the DIFFERENCE between moles of solid DISSOLVED to form a saturated solution and the resulting MOLARITY of the dissolved IONS IN SOLUTION.
It is crucial for you to see/feel this major difference, which is due to the fact that we NEVER calculate or even care about the "molarity" of the solid! Solids, by definition, are not aqueous so the molarity cannot change; thus we ONLY ever consider the grams or moles of solid DISSOLVED to form certain concentrations of the DISSOLVED ions.
We reviewed how to write K expressions, which we will call Ksp for sparingly soluble salts. We also reviewed that the CHARGE DENSITY of the ions in the salt lattice is the major determinant of the salt's solubility in polar solvents.
Bio 6- we discussed the process of embryonic development from fertilization to blastula formation to gastrulation, noting that blastula cells are identical cells formed via MITOSIS. However, a gastrula soon forms containing different types of cells in the three layers: endoderm, mesoderm, and ectoderm. These cell have different structures and form different organ systems of the body because the cells of the blastula begin to experience different chemical and physical environments, which causes certain genes to be turned off or turned on in a given cell. Thus a cell with different genes turned on will translate different proteins and have a different structure and function than another cell that has other genes turned on.
We then began to watch the amazing videography in the video about reproduction and development of the humans.
Bio 7/8- we discussed the process of embryonic development from fertilization to blastula formation to gastrulation, noting that blastula cells are identical cells formed via MITOSIS. However, a gastrula soon forms containing different types of cells in the three layers: endoderm, mesoderm, and ectoderm. These cell have different structures and form different organ systems of the body because the cells of the blastula begin to experience different chemical and physical environments, which causes certain genes to be turned off or turned on in a given cell. Thus a cell with different genes turned on will translate different proteins and have a different structure and function than another cell that has other genes turned on.
We then began to watch the amazing videography in the video about reproduction and development of the humans.
Truth in advertising:
your test tomorrow will have-
1. a polyprotic acid problem (as seen in the notes) in which all eq. quantities are solved for.
2. a FULL titration of either a weak acid or a weak base and calculations at the typical points of interest.
3. a buffer solution pH calculation before and after addition of a strong acid or base (exactly as done in the notes)
4. Lewis acid and base theory in words and Lewis structures.
5. Titration curves and selection of appropriate indicators.
6. Selecting the correct substances in order to make a buffer of a particular pH.
Be prepared and do well on this challenging exam because the next test is even more challenging for sure.
Finished the acid-base unit by discussing the polyprotic acid titration curve and noting the various buffer regions. We also saw how buffers of a particular pH can be made by choosing suitable combinations of salts of the conjugate amphoteric bases of the polyprotic acid.
Depending on the desired pH, you should choose a salt that has an acidic (even though the ion is amphoteric, just consider it acting as an acid in this case) ion that has a pKa near the desired pH along with a salt that contains the conjugate base of that acidic ion.
We then began the ultimate challenge (as you quickly saw, perhaps?) of our course: sparingly soluble salt equilibria (NOT on tomorrow's exam).
We introduced this topic by painstakingly pointing out the DIFFERENCE between moles of solid DISSOLVED to form a saturated solution and the resulting MOLARITY of the dissolved IONS IN SOLUTION.
It is crucial for you to see/feel this major difference, which is due to the fact that we NEVER calculate or even care about the "molarity" of the solid! Solids, by definition, are not aqueous so the molarity cannot change; thus we ONLY ever consider the grams or moles of solid DISSOLVED to form certain concentrations of the DISSOLVED ions.
We reviewed how to write K expressions, which we will call Ksp for sparingly soluble salts. We also reviewed that the CHARGE DENSITY of the ions in the salt lattice is the major determinant of the salt's solubility in polar solvents.
Bio 6- we discussed the process of embryonic development from fertilization to blastula formation to gastrulation, noting that blastula cells are identical cells formed via MITOSIS. However, a gastrula soon forms containing different types of cells in the three layers: endoderm, mesoderm, and ectoderm. These cell have different structures and form different organ systems of the body because the cells of the blastula begin to experience different chemical and physical environments, which causes certain genes to be turned off or turned on in a given cell. Thus a cell with different genes turned on will translate different proteins and have a different structure and function than another cell that has other genes turned on.
We then began to watch the amazing videography in the video about reproduction and development of the humans.
Bio 7/8- we discussed the process of embryonic development from fertilization to blastula formation to gastrulation, noting that blastula cells are identical cells formed via MITOSIS. However, a gastrula soon forms containing different types of cells in the three layers: endoderm, mesoderm, and ectoderm. These cell have different structures and form different organ systems of the body because the cells of the blastula begin to experience different chemical and physical environments, which causes certain genes to be turned off or turned on in a given cell. Thus a cell with different genes turned on will translate different proteins and have a different structure and function than another cell that has other genes turned on.
We then began to watch the amazing videography in the video about reproduction and development of the humans.
# posted by C @ 10:34 AM 
