Monday, March 23, 2009
Mon-Day 1
AP Chem- saw how to quickly compare the solubilities of various salts by comparing their Ksp values IF (!!!) the salts have the same SUBSCRIPTS in their empirical formulas i.e. Ksp expression EXPONENTS. If the salts have different empirical formulas, then a qualitative estimate cannot easily be calculated!
We then calculated the solubility of a salt by itself and then WITH a COMMON ION in solution; the result can be predicted from Le Chatelier's Rule. A common ion will shift equilibrium towards the undissolved precipitate. Thus, when a common ion is in solution, the SOLUBILITY of a sparingly soluble salt is depressed/lowered.
We then played the "will a precipitate form?" game by comparing the given Ksp with the current Qsp of the salt in solution. For precipitates that did form, we calculated the MOST DIFFICULT PROBLEM TYPE FOR THIS UNIT: the number of grams of precipitate formed AND the percent precipitation/ determination of "complete" precipitation.
For this part of the problem, we precipitated/use up ALL OF ONE OF THE IONS (SRFC TABLE!) and then, naturally, some/ a WEE BIT of the precipitate re-dissolves (ICE TABLE!).
The problem is that STOICHIOMETRY must be adhered to in these tables AND in the Ksp expressions!
It is important to DRAW OUT the ions in solution so that you can SEE what is going on; remember the ERRORS that were caused on the last test by not SEEING/DRAWING what was occurring.
Bio 6/7/8- we reviewed the Repro/Meiosis exam, discussing the various test-taking skills that should have been applied; these practices can ONLY HELP YOUR SCORE! This is INDISPUTABLE and is supported by a mountain of evidence and pure logic, NOT CONJECTURE OR OPINION! These skills (especially identifying and USING the key words/data in a question as well as DRAWING things out) should ALWAYS be used and practiced so that they are a natural/ not time-consuming way for you to take tests.
We then began our new unit on Genetics by discussing Mendel's scientific method that led to the discovery of some of the basic laws of heredity/genetics.
We then calculated the solubility of a salt by itself and then WITH a COMMON ION in solution; the result can be predicted from Le Chatelier's Rule. A common ion will shift equilibrium towards the undissolved precipitate. Thus, when a common ion is in solution, the SOLUBILITY of a sparingly soluble salt is depressed/lowered.
We then played the "will a precipitate form?" game by comparing the given Ksp with the current Qsp of the salt in solution. For precipitates that did form, we calculated the MOST DIFFICULT PROBLEM TYPE FOR THIS UNIT: the number of grams of precipitate formed AND the percent precipitation/ determination of "complete" precipitation.
For this part of the problem, we precipitated/use up ALL OF ONE OF THE IONS (SRFC TABLE!) and then, naturally, some/ a WEE BIT of the precipitate re-dissolves (ICE TABLE!).
The problem is that STOICHIOMETRY must be adhered to in these tables AND in the Ksp expressions!
It is important to DRAW OUT the ions in solution so that you can SEE what is going on; remember the ERRORS that were caused on the last test by not SEEING/DRAWING what was occurring.
Bio 6/7/8- we reviewed the Repro/Meiosis exam, discussing the various test-taking skills that should have been applied; these practices can ONLY HELP YOUR SCORE! This is INDISPUTABLE and is supported by a mountain of evidence and pure logic, NOT CONJECTURE OR OPINION! These skills (especially identifying and USING the key words/data in a question as well as DRAWING things out) should ALWAYS be used and practiced so that they are a natural/ not time-consuming way for you to take tests.
We then began our new unit on Genetics by discussing Mendel's scientific method that led to the discovery of some of the basic laws of heredity/genetics.
# posted by C @ 10:30 PM 
