Tuesday, October 28, 2008
Tues-Day 1
AP Chem- we finished our determination of the percent hypochorite ion in bleach data collection/titration.
There were two redox reactions involved in the lab:
1. As you saw, the first reaction occurred between the hypochlorite ion of bleach with the iodide ion from the KI salt to form chloride ion and triiodide ion (-1 charge).
2. You then titrated this triiodide ion with the thiosulfate ion from the buret solution to form iodide ion and "dithionate" ion ( S4O6 2-). To SEE the endpoint/equivalence point of the titration, we used starch solution, which complexes with the I3 - ion to form a blue-black complex. When all of the I3- was reacted with the thiosulfate, there was then no more blue-black complex that could form so the solution went totally colorLESS!
We finished up our double replacement with precipitation/limiting reactant problem by calculating the concentrations of all remaining aqueous ions. Remember: for SPECTATOR IONS, just divide the ORIGINAL/initial number of moles of each ion by the NEW larger volume (due to the mixing of the two reactant solutions!). That gives you the new concentration of each spectator ion. DO NOT USE THE COEFFICIENTS OF THE BALANCED EQUATION. THEY CAN ONLY BE USED TO DETERMINE LIMITING/EXCESS REACTANTS and to determine the moles of each product formed!
These coefficients CHANGE FOR EACH DIFFERENT REACTION so they can NEVER EVER be used to determine molar mass nor can they ever influence the molar mass of a compound.
We then did an acid base neutralization titration/stoichiometry problem in which the empirical formula of an unknown acid via titration by a known base of known molarity.
Remember, the titration neutralization formula is:
# of moles of H+ from the acid = # of moles of OH- from the base
at the equivalence/end point of the titration!
Some of you are not practicing enough. One of the toughest parts of this course is making enough time to do 5 to 10 of EACH and EVERY different problem type so that you are agile, fast, and accurate with the various problem types and their myriad permutations.
Bio 6/7- we reviewed and discussed the three overall purposes of mitosis especially in complex, multi-cellular organisms. We then looked at the final part of our unit: asexual reproduction.
There are FIVE different types of asexual reproduction, ALL of which involve forming genetically identical new cells from the original cells. There is no such thing as male and female in asexual reproduction; there is just one parent cell that is NOT a sex cell.
We saw binary fission that occurs in bacteria, amebas, paramecia, and euglenas. Budding occurs in yeast and hydra. Sporulation in fungi. Regeneration in starfish and planaria. We also discussed THREE types of asexual vegetative propagation, which has the advantage of producing clones of very healthy or delicious plants/veggies/fruits: cutting, grafting, and layering. We almost finished our state osmosis lab discussion and our plant vs. animal cell lab questions.
Bio 8- we reviewed and discussed the three overall purposes of mitosis especially in complex, multi-cellular organisms. We then looked at the final part of our unit: asexual reproduction.
There are FIVE different types of asexual reproduction, ALL of which involve forming genetically identical new cells from the original cells. There is no such thing as male and female in asexual reproduction; there is just one parent cell that is NOT a sex cell.
We saw binary fission that occurs in bacteria, amebas, paramecia, and euglenas. Budding occurs in yeast and hydra. Sporulation in fungi. Regeneration in starfish and planaria.
There were two redox reactions involved in the lab:
1. As you saw, the first reaction occurred between the hypochlorite ion of bleach with the iodide ion from the KI salt to form chloride ion and triiodide ion (-1 charge).
2. You then titrated this triiodide ion with the thiosulfate ion from the buret solution to form iodide ion and "dithionate" ion ( S4O6 2-). To SEE the endpoint/equivalence point of the titration, we used starch solution, which complexes with the I3 - ion to form a blue-black complex. When all of the I3- was reacted with the thiosulfate, there was then no more blue-black complex that could form so the solution went totally colorLESS!
We finished up our double replacement with precipitation/limiting reactant problem by calculating the concentrations of all remaining aqueous ions. Remember: for SPECTATOR IONS, just divide the ORIGINAL/initial number of moles of each ion by the NEW larger volume (due to the mixing of the two reactant solutions!). That gives you the new concentration of each spectator ion. DO NOT USE THE COEFFICIENTS OF THE BALANCED EQUATION. THEY CAN ONLY BE USED TO DETERMINE LIMITING/EXCESS REACTANTS and to determine the moles of each product formed!
These coefficients CHANGE FOR EACH DIFFERENT REACTION so they can NEVER EVER be used to determine molar mass nor can they ever influence the molar mass of a compound.
We then did an acid base neutralization titration/stoichiometry problem in which the empirical formula of an unknown acid via titration by a known base of known molarity.
Remember, the titration neutralization formula is:
# of moles of H+ from the acid = # of moles of OH- from the base
at the equivalence/end point of the titration!
Some of you are not practicing enough. One of the toughest parts of this course is making enough time to do 5 to 10 of EACH and EVERY different problem type so that you are agile, fast, and accurate with the various problem types and their myriad permutations.
Bio 6/7- we reviewed and discussed the three overall purposes of mitosis especially in complex, multi-cellular organisms. We then looked at the final part of our unit: asexual reproduction.
There are FIVE different types of asexual reproduction, ALL of which involve forming genetically identical new cells from the original cells. There is no such thing as male and female in asexual reproduction; there is just one parent cell that is NOT a sex cell.
We saw binary fission that occurs in bacteria, amebas, paramecia, and euglenas. Budding occurs in yeast and hydra. Sporulation in fungi. Regeneration in starfish and planaria. We also discussed THREE types of asexual vegetative propagation, which has the advantage of producing clones of very healthy or delicious plants/veggies/fruits: cutting, grafting, and layering. We almost finished our state osmosis lab discussion and our plant vs. animal cell lab questions.
Bio 8- we reviewed and discussed the three overall purposes of mitosis especially in complex, multi-cellular organisms. We then looked at the final part of our unit: asexual reproduction.
There are FIVE different types of asexual reproduction, ALL of which involve forming genetically identical new cells from the original cells. There is no such thing as male and female in asexual reproduction; there is just one parent cell that is NOT a sex cell.
We saw binary fission that occurs in bacteria, amebas, paramecia, and euglenas. Budding occurs in yeast and hydra. Sporulation in fungi. Regeneration in starfish and planaria.
# posted by C @ 10:47 AM 
