Surface Area/Volume Lab
Compiled notes from pre-lab discussions/general feedback on written lab reports.
General Research Question: Why are cells generally so small?
Specific Research Question: What pattern do we see when we look at absorption of a NaOH solution into a model cell system made from agar cubes and a pH indicator?
Independent Variable: size of the cube
Dependent Variable: percent of the cube that absorbed NaOH
(Review of types of errors)
Error in the Independent Variable: With the rulers error is +/- one-half of the smallest unit on the ruler, +/- 0.5 mm. This value is carried through without, further mathematical manipulation, as surface area, volumes, percent of the linear distance showing absorption, etc. (A great simplification, compared with what you may be doing in IB Chem/IB Phys!)
Error in the Dependent Variable: Use multiple measurements of the distance absorbed, with a maximum distance from the edge to the center of the cube. Since the cubes were different sizes, these were made comparable by calculating the proportion or percentage of the maximum distance absorbed. Whenever there are replicate measurements, a mean should be calculated. Whenever there is a mean, a standard deviation from that mean should also be calculated. The standard deviation is the value used for the error bars on the dependent variable coordinates (y axis). Make sure the SD values correspond to the values used to calculate the mean.
Clearly present the three aspects of the conclusion and evaluation section, paying attention the the checkbox details in each aspect, as shown in the rubric. (More notes on this to follow as we do more labs.)
General Research Question: Why are cells generally so small?
Specific Research Question: What pattern do we see when we look at absorption of a NaOH solution into a model cell system made from agar cubes and a pH indicator?
Independent Variable: size of the cube
Dependent Variable: percent of the cube that absorbed NaOH
(Review of types of errors)
Error in the Independent Variable: With the rulers error is +/- one-half of the smallest unit on the ruler, +/- 0.5 mm. This value is carried through without, further mathematical manipulation, as surface area, volumes, percent of the linear distance showing absorption, etc. (A great simplification, compared with what you may be doing in IB Chem/IB Phys!)
Error in the Dependent Variable: Use multiple measurements of the distance absorbed, with a maximum distance from the edge to the center of the cube. Since the cubes were different sizes, these were made comparable by calculating the proportion or percentage of the maximum distance absorbed. Whenever there are replicate measurements, a mean should be calculated. Whenever there is a mean, a standard deviation from that mean should also be calculated. The standard deviation is the value used for the error bars on the dependent variable coordinates (y axis). Make sure the SD values correspond to the values used to calculate the mean.
Clearly present the three aspects of the conclusion and evaluation section, paying attention the the checkbox details in each aspect, as shown in the rubric. (More notes on this to follow as we do more labs.)
