Molarity Mixup and Water Potential Argument

Activity 1: Molarity Mixup

Claim:

In this lab my partner and I were given six sucrose solutions of concentrations spanning from 0.0M to 1.0M in 0.2M increments in different colors (0.0M, 0.2M, 0.4M, 0.6M, 0.8M, 1.0M). We had to determine the molarity of each solution with our understanding of water potential and tonicity. We argue that the green solution was 0.0M, orange was 0.2M, purple was 0.4M, blue was 0.6M, red was 0.8M, and yellow was 1.0M.

Evidence:

	Initial Mass(g)	Final Mass(g)	% Change in Mass
Bag 1- Red	11.94	5.3	-56 %
Bag 2- Orange	13.56	8.9	-34%
Bag 3- Yellow	10.85	4	-63%
Bag 4- Green	14.61	14.5	-11%
Bag 5- Blue	13.1	7.9	-39%
Bag 6- Purple	13.7	8.5	-38%

My partner and I weighed each bag before and after putting them in the sucrose solutions. We did this because we would be able to detect the change in mass of each bag after it was put into the solution. The change in mass was calculated by subtracting the final mass from the initial mass divided by the initial mass and that number multiplied by 10
.

Reasoning:

By examining the change in mass percentages, my partner and I matched up the percentages with the molarities of each solution. The heavier the bag weighed the higher its molar sucrose solution was. Bag 4 (Green) had the lowest percentage of change in mass, -11%, and we matched that to the 0.0M sucrose solution. Bag 2 (Orange) had -34% change in mass and we matched that to the 0.2M sucrose solution. Bag 6 (Purple) had -38% change in mass and we matched that to the 0.4M sucrose solution. Bag 5 (Blue) had -39% change in mass and we matched that to the 0.6M sucrose solution. Bag 1 (Red) had -56% change in mass and we matched that to the 0.8M sucrose solution. Bag 3 (Yellow) had -63% change in mass and we matched that to the 1.0M sucrose solution.

Water moves from areas of high concentration to areas of low concentration. Sucrose solutions that had more sucrose, 1.0M for example,  had fewer amount of water left in it’s dialysis tube after the trial. This is because there was high concentration of water in the bag in the beginning of the lab and moved out into the lower water concentration solution. Sucrose solutions that had less sucrose, 0.2M for example, had more water left in its dialysis tube after the experiment compared to higher sucrose solutions. The water concentration in the dialysis tube is still higher compared to its sucrose solution however less water moves out because there is not a dramatic difference in water concentration.

Activity 2: Water Potential of a Turnip

Claim:

In this activity my partner and I had to determine the water potential of a turnip. The water potential of the turnip was -11.03 bars.

Evidence:

	Initial Mass(g)	Final Mass(g)	% Change in Mass
Slice 1	3.81	2.8	-27%
Slice 2	4.65	4.8	3%
Slice 3	3.42	2.3	-33%
Slice 4	3.45	4	16%
Slice 5	2.84	2.7	-4%
Slice 6	4.99	5.1	2%

My partner and I weighed each slice of turnip before and after putting them into the sucrose solutions to determine their percent change in mass. The change in mass was calculated by subtracting the final mass from the initial mass divided by the initial mass and that number multiplied by 10.

Shown above is a graph displaying the change in mass percentages of all six sucrose solutions. The molar concentration that would be in equilibrium with no percent change in mass would be 0.45 because that was the point at which the line crossed the x-axis.

Reasoning:

Using the -iCRT equation we determined the water potential of the turnip. Our ionization constant  was 1 because we were using sucrose, molar concentration was 0.45, R was 0.0831 because it is our constant, and temperature was 295 (20 degrees plus 273). We multiplied all of these components and received the water potential of the turnip which was -11.03 bars.