Wednesday, October 17, 2007
Wednes-Day 2
Bio- we reviewed osmosis of water from hypotonic (little salt, mostly water) solutions TO hypertonic (very salty, less water) solutions (on a test, ALWAYS LABEL which region is hypotonic and which region is hypertonic because there is ALWAYS a NET flow of water from hypotonic TO hypertonic regions (just draw an arrow and you will always get these questions right)!
We discussed the TWO types of PASSIVE TRANSPORT: SIMPLE DIFFUSION (if the substance is water, OSMOSIS) and, for molecules (e.g. glucose) that require a special transport protein channel BUT no use of energy from ATP, FACILITATED DIFFUSION (the transport protein FACILITATES, makes easier, the transport of the molecule or ion DOWN the concentration gradient.
We discussed Active Transport, which requires ENERGY via the breakdown of ATP-the main energy molecule of ALL organisms. Active Transport is the NET movement of a substance UP A CONCENTRATION GRADIENT. That is, net movement of the substance from a region of LOWER concentration TO a region of HIGHER concentration.
We then began a discussion of cell specialization, which is characteristic of complex, multi-cellular organisms. That is, as multi-cellular organisms develop, cells differentiate and each different cell type performs a different task. For example, human red blood cells are designed to transport oxygen to other cells in the body where as human nerve cells transmit electrochemical impulses throughout the body (in response to stimuli).
A paramecium consists of a single cell and thus performs all of its required life functions via its organelles within the cell.
Tomorrow, we will discuss "levels of organization" in multi-cellular organisms.
We will also do the NY State Regents required osmosis and chemical indicator lab. Be ready for lab as soon as the bell rings!
Chem 7/8- we did a quantitative problem involving Table I, potential energy diagrams, and calculations for a given quantity of reactant or product in the thermochemical equation.
Keep doing problems like that in the hw packet!
I will give you a comprehensive handout on those problems, tomorrow.
We then began kinetics, the study of reaction rates and the mechanisms of reactions.
We learned that chemical reactions are actually EFFECTIVE COLLISIONS between reactant particles.
To have an EFFECTIVE collision, particles must collide with SUFFICIENT kinetic energy for bond breakage (the minimum quantity of energy for bond breakage is the reaction's ACTIVATION ENERGY!) AND ALSO the particles must collide with the proper geometric spatial orientation (so that the "correct" bonds break to form the desired products).
We demonstrated TWO of the FOUR factors that will AFFECT the number of effective collisions that occur per second (the REACTION RATE, literally):
Temperature and Concentration!
Increasing temperature will increase the average kinetic energy of the particles so the particles will naturally collide more frequently (less time between collisions since the particles sped up).
ALSO, increasing the temperature (average KE) will increase the FRACTION of particles that have SUFFICIENT kinetic energy for an effective collision (e.g. from 1/20 to 1/3). Therefore, the number of effective collisions per second (the reaction rate) increases.
However, temperature has no EFFECT on the FRACTION of molecules that are colliding with proper orientation so that fraction remains the same (e.g. one-fourth before, one-fourth after); the other factor, though, is more than enough to increase the reaction rate.
Decreasing temperature has the opposite effect of what was described above, naturally.
Increasing concentration means that there are MORE PARTICLES per mL than before! Therefore, there will be MORE collisions between particles every second.
Even though increasing concentration has NO EFFECT on the SPEED/KINETIC ENERGY of the particles and NO EFFECT on the fraction of particles with proper orientation, the fact that there are more collisions per second (e.g. from 5 collisions per second to 1000 collisions per second) will lead more EFFECTIVE collisions per second.
Decreasing concentration has the opposite effect of what was described above.
We then discussed the heat of solution of NaOH lab. We changed "moles" to grams, for our write-up. We also acknowledged that, even though we are using the specific heat of water, we really should use the value of the specific heat of the solution but we assume that those two values are almost the same for our degree of precision.
Chem 9- we did a quantitative problem involving Table I, potential energy diagrams, and calculations for a given quantity of reactant or product in the thermochemical equation.
Keep doing problems like that in the hw packet!
I will give you a comprehensive handout on those problems, tomorrow.
We then began kinetics, the study of reaction rates and the mechanisms of reactions.
We learned that chemical reactions are actually EFFECTIVE COLLISIONS between reactant particles.
To have an EFFECTIVE collision, particles must collide with SUFFICIENT kinetic energy for bond breakage (the minimum quantity of energy for bond breakage is the reaction's ACTIVATION ENERGY!) AND ALSO the particles must collide with the proper geometric spatial orientation (so that the "correct" bonds break to form the desired products).
Tomorrow, we will discuss and demonstrate the four factors that can affect the number of effective collisions per second between reactant particles i.e. the reaction rate.
We discussed the TWO types of PASSIVE TRANSPORT: SIMPLE DIFFUSION (if the substance is water, OSMOSIS) and, for molecules (e.g. glucose) that require a special transport protein channel BUT no use of energy from ATP, FACILITATED DIFFUSION (the transport protein FACILITATES, makes easier, the transport of the molecule or ion DOWN the concentration gradient.
We discussed Active Transport, which requires ENERGY via the breakdown of ATP-the main energy molecule of ALL organisms. Active Transport is the NET movement of a substance UP A CONCENTRATION GRADIENT. That is, net movement of the substance from a region of LOWER concentration TO a region of HIGHER concentration.
We then began a discussion of cell specialization, which is characteristic of complex, multi-cellular organisms. That is, as multi-cellular organisms develop, cells differentiate and each different cell type performs a different task. For example, human red blood cells are designed to transport oxygen to other cells in the body where as human nerve cells transmit electrochemical impulses throughout the body (in response to stimuli).
A paramecium consists of a single cell and thus performs all of its required life functions via its organelles within the cell.
Tomorrow, we will discuss "levels of organization" in multi-cellular organisms.
We will also do the NY State Regents required osmosis and chemical indicator lab. Be ready for lab as soon as the bell rings!
Chem 7/8- we did a quantitative problem involving Table I, potential energy diagrams, and calculations for a given quantity of reactant or product in the thermochemical equation.
Keep doing problems like that in the hw packet!
I will give you a comprehensive handout on those problems, tomorrow.
We then began kinetics, the study of reaction rates and the mechanisms of reactions.
We learned that chemical reactions are actually EFFECTIVE COLLISIONS between reactant particles.
To have an EFFECTIVE collision, particles must collide with SUFFICIENT kinetic energy for bond breakage (the minimum quantity of energy for bond breakage is the reaction's ACTIVATION ENERGY!) AND ALSO the particles must collide with the proper geometric spatial orientation (so that the "correct" bonds break to form the desired products).
We demonstrated TWO of the FOUR factors that will AFFECT the number of effective collisions that occur per second (the REACTION RATE, literally):
Temperature and Concentration!
Increasing temperature will increase the average kinetic energy of the particles so the particles will naturally collide more frequently (less time between collisions since the particles sped up).
ALSO, increasing the temperature (average KE) will increase the FRACTION of particles that have SUFFICIENT kinetic energy for an effective collision (e.g. from 1/20 to 1/3). Therefore, the number of effective collisions per second (the reaction rate) increases.
However, temperature has no EFFECT on the FRACTION of molecules that are colliding with proper orientation so that fraction remains the same (e.g. one-fourth before, one-fourth after); the other factor, though, is more than enough to increase the reaction rate.
Decreasing temperature has the opposite effect of what was described above, naturally.
Increasing concentration means that there are MORE PARTICLES per mL than before! Therefore, there will be MORE collisions between particles every second.
Even though increasing concentration has NO EFFECT on the SPEED/KINETIC ENERGY of the particles and NO EFFECT on the fraction of particles with proper orientation, the fact that there are more collisions per second (e.g. from 5 collisions per second to 1000 collisions per second) will lead more EFFECTIVE collisions per second.
Decreasing concentration has the opposite effect of what was described above.
We then discussed the heat of solution of NaOH lab. We changed "moles" to grams, for our write-up. We also acknowledged that, even though we are using the specific heat of water, we really should use the value of the specific heat of the solution but we assume that those two values are almost the same for our degree of precision.
Chem 9- we did a quantitative problem involving Table I, potential energy diagrams, and calculations for a given quantity of reactant or product in the thermochemical equation.
Keep doing problems like that in the hw packet!
I will give you a comprehensive handout on those problems, tomorrow.
We then began kinetics, the study of reaction rates and the mechanisms of reactions.
We learned that chemical reactions are actually EFFECTIVE COLLISIONS between reactant particles.
To have an EFFECTIVE collision, particles must collide with SUFFICIENT kinetic energy for bond breakage (the minimum quantity of energy for bond breakage is the reaction's ACTIVATION ENERGY!) AND ALSO the particles must collide with the proper geometric spatial orientation (so that the "correct" bonds break to form the desired products).
Tomorrow, we will discuss and demonstrate the four factors that can affect the number of effective collisions per second between reactant particles i.e. the reaction rate.
# posted by C @ 12:09 PM 
