Pre-Lab: "Party Gel"
Reactants: Agarose + Phenolphtalein + NaOH
In the demo, the "party gel" was cut into two shapes: a leaf and a semi-circle. When the vinegar penetrated the phenolphtalein, the pink color of the gel began to disappear. In the picture below (and to the right, which was taken after 10 minutes, shows the reaction slowly beginning on the outside of the leaf-shape where the vinegar had been poured, and the semi-circle is almost completely colorless. Surface area seems to play an important role in the amount of time it takes for the reaction to occur thoroughly. The picture in the center shows the reaction progression after 30 minutes; the picture below (and to the left) was taken 24 hrs after the reaction began and shows that reaction was completed and the shapes were colorless/white.
In the demo, the "party gel" was cut into two shapes: a leaf and a semi-circle. When the vinegar penetrated the phenolphtalein, the pink color of the gel began to disappear. In the picture below (and to the right, which was taken after 10 minutes, shows the reaction slowly beginning on the outside of the leaf-shape where the vinegar had been poured, and the semi-circle is almost completely colorless. Surface area seems to play an important role in the amount of time it takes for the reaction to occur thoroughly. The picture in the center shows the reaction progression after 30 minutes; the picture below (and to the left) was taken 24 hrs after the reaction began and shows that reaction was completed and the shapes were colorless/white.
Lab Procedure/ Experiment
(Left to Right) Solutions A-D, inside the graduated cylinder is a slice of potato.
~ Super Sugary - (Potato) Shrinks, Weighs Less/Floats
~ Low Sugar - (Potato) Swells, Weighs More/Sinks
~ No Sugar - (Potato) Stays Same
Each beaker was filled with an unknown solution of varying solute concentrations. Each potato was weighed at 2.1-2.4g (See chart below) and dropped in the solution . Diffusion took place for 40 minutes, and the potatoes were weighed again.
~ Super Sugary - (Potato) Shrinks, Weighs Less/Floats
~ Low Sugar - (Potato) Swells, Weighs More/Sinks
~ No Sugar - (Potato) Stays Same
Each beaker was filled with an unknown solution of varying solute concentrations. Each potato was weighed at 2.1-2.4g (See chart below) and dropped in the solution . Diffusion took place for 40 minutes, and the potatoes were weighed again.
Conclusion
a. Most concentrated to least concentrated: A or E, C, D, B
b. Calculated solute potential:
~ A. (0.8M) ~ B. (0.2M) ~ C. (0.6M) ~ D. (0.4M) ~ E. (1.0M)
= -iCRT = -iCRT = -iCRT = -iCRT = -iCRT
= -1(0.8)(0.083)(295) = -1(0.2)(0.083)(295) = -1(0.6)(0.083)(295) = -1(0.4)(0.083)(295) = -1(1.0)(0.083)(295)
= -19.6116 = -4.9029 = -14.7087 = -9.8058 = -24.5145
c. If the plant cells used in the experiment was left over the weekend, the plant cells in a hypotonic solution would not burst because of the plant cell wall. The hypotonic solution would create turgid pressure within the vacuole of the plant cell.
d. This experiment could not be done effectively with animal cells/tissues due to the lack of a cell wall; the animal cell would burst in a hypotonic solution. Animal cells do not have a large vacuole like a plant cell, therefore they cannot hold as much water.
e. A source of error could have been taking the potato slices out of the graduated cylinders after 6 min and then putting the potato slices back in for an extra 34 minutes.
b. Calculated solute potential:
~ A. (0.8M) ~ B. (0.2M) ~ C. (0.6M) ~ D. (0.4M) ~ E. (1.0M)
= -iCRT = -iCRT = -iCRT = -iCRT = -iCRT
= -1(0.8)(0.083)(295) = -1(0.2)(0.083)(295) = -1(0.6)(0.083)(295) = -1(0.4)(0.083)(295) = -1(1.0)(0.083)(295)
= -19.6116 = -4.9029 = -14.7087 = -9.8058 = -24.5145
c. If the plant cells used in the experiment was left over the weekend, the plant cells in a hypotonic solution would not burst because of the plant cell wall. The hypotonic solution would create turgid pressure within the vacuole of the plant cell.
d. This experiment could not be done effectively with animal cells/tissues due to the lack of a cell wall; the animal cell would burst in a hypotonic solution. Animal cells do not have a large vacuole like a plant cell, therefore they cannot hold as much water.
e. A source of error could have been taking the potato slices out of the graduated cylinders after 6 min and then putting the potato slices back in for an extra 34 minutes.