Tuesday, May 13, 2008
Tues-Day 1
Bio- we discussed food chains and food webs and explained the possible outcomes of a disturbance to a food web. If one population in a community decreases or goes extinct, some populations in the community can be adversely affected and other populations may temporarily benefit.
We discussed the concept of an energy pyramid and a biomass pyramid. Both pyramids exhibit the same thing: the organisms that make up the largest (base) part of the pyramid are the PRODUCERS because only producers can photosynthesize their own food (i.e. they are autotrophs) from abundant, simple inorganic molecules such as carbon dioxide and water. Each subsequent level of consumer has less total energy and mass because most of the energy and mass consumed is then lost as heat/energy.
We also discussed biomagnification, which is the concentration of non-degradable contaminants or pollutants as they are passed from the producer level through the consumer levels.
We then continued to discuss the "beaks of finches/natural selection" lab.
Chem 7- I put a LOT of review worksheets and practice tests on Blackboard; review them before your test on Thursday.
We discussed and did examples involving pH and hydronium ion concentrations. We learned how to estimate pH from H+ ion concentrations by focusing on the EXPONENT of the concentration. For example, if the [H+] = 2.0 x 10-4, then the pH MUST be between 3 and 4 (because the exponent is -4) and is likely near 3.8.
We filled out a pH and pOH chart, which you can use to help with pH calculations on your test if you can quickly draw out the pattern.
We also saw the all-important feature of pH that a change of 1.0 pH unit is a TEN-fold change in H+ concentration or "acidity"! So, a change of 2 pH units is a 100x change, a change of 3 pH units is a 1000x change, a change of 4 pH units is a 10000x change (note that the number of zeroes equals the number of pH units changed!).
We then reviewed some Bronsted acid/base concepts and problems.
Chem 8/9- I put a LOT of review worksheets and practice tests on Blackboard; review them before your test on Thursday.
We discussed and did examples involving pH and hydronium ion concentrations. We learned how to estimate pH from H+ ion concentrations by focusing on the EXPONENT of the concentration. For example, if the [H+] = 2.0 x 10-4, then the pH MUST be between 3 and 4 (because the exponent is -4) and is likely near 3.8.
We filled out a pH and pOH chart, which you can use to help with pH calculations on your test if you can quickly draw out the pattern.
We also saw the all-important feature of pH that a change of 1.0 pH unit is a TEN-fold change in H+ concentration or "acidity"! So, a change of 2 pH units is a 100x change, a change of 3 pH units is a 1000x change, a change of 4 pH units is a 10000x change (note that the number of zeroes equals the number of pH units changed!).
We then reviewed some Bronsted acid/base concepts and problems.
We performed an acid-base titration in lab; we will apply the titration formula to our data in order to determine the molarity of the acid that we titrated with .60M NaOH (aq).
We discussed the concept of an energy pyramid and a biomass pyramid. Both pyramids exhibit the same thing: the organisms that make up the largest (base) part of the pyramid are the PRODUCERS because only producers can photosynthesize their own food (i.e. they are autotrophs) from abundant, simple inorganic molecules such as carbon dioxide and water. Each subsequent level of consumer has less total energy and mass because most of the energy and mass consumed is then lost as heat/energy.
We also discussed biomagnification, which is the concentration of non-degradable contaminants or pollutants as they are passed from the producer level through the consumer levels.
We then continued to discuss the "beaks of finches/natural selection" lab.
Chem 7- I put a LOT of review worksheets and practice tests on Blackboard; review them before your test on Thursday.
We discussed and did examples involving pH and hydronium ion concentrations. We learned how to estimate pH from H+ ion concentrations by focusing on the EXPONENT of the concentration. For example, if the [H+] = 2.0 x 10-4, then the pH MUST be between 3 and 4 (because the exponent is -4) and is likely near 3.8.
We filled out a pH and pOH chart, which you can use to help with pH calculations on your test if you can quickly draw out the pattern.
We also saw the all-important feature of pH that a change of 1.0 pH unit is a TEN-fold change in H+ concentration or "acidity"! So, a change of 2 pH units is a 100x change, a change of 3 pH units is a 1000x change, a change of 4 pH units is a 10000x change (note that the number of zeroes equals the number of pH units changed!).
We then reviewed some Bronsted acid/base concepts and problems.
Chem 8/9- I put a LOT of review worksheets and practice tests on Blackboard; review them before your test on Thursday.
We discussed and did examples involving pH and hydronium ion concentrations. We learned how to estimate pH from H+ ion concentrations by focusing on the EXPONENT of the concentration. For example, if the [H+] = 2.0 x 10-4, then the pH MUST be between 3 and 4 (because the exponent is -4) and is likely near 3.8.
We filled out a pH and pOH chart, which you can use to help with pH calculations on your test if you can quickly draw out the pattern.
We also saw the all-important feature of pH that a change of 1.0 pH unit is a TEN-fold change in H+ concentration or "acidity"! So, a change of 2 pH units is a 100x change, a change of 3 pH units is a 1000x change, a change of 4 pH units is a 10000x change (note that the number of zeroes equals the number of pH units changed!).
We then reviewed some Bronsted acid/base concepts and problems.
We performed an acid-base titration in lab; we will apply the titration formula to our data in order to determine the molarity of the acid that we titrated with .60M NaOH (aq).
# posted by C @ 3:06 PM 
