Diffusion And Osmosis Lab Answers
Lab One – Diffusion and Osmosis
SECTION ONE: Methods
Lab 1 – Diffusion and Osmosis can be broken down into four parts (A, B, C, and D).
Lab 1A – Diffusion In this exercise, we tested diffusion through dialysis tubing. This was done through a demo with the teacher, rather than individually in groups. First, a piece of 2.5cm dialysis tubing was obtained. Then one end was folded and clipped securely so that a solution poured into the bag would not leak out. Next, the other side of the bag was opened. For step two, a 15% glucose/1% starch solution was tested for the presence of glucose with Benedict’s, and we recorded the data in a table. Using more 15% glucose/1% starch solution, 15 mL was placed in the dialysis bag. The other end was tied, …show more content…
leaving room for the contents in the bag to expand. The color of the contents was recorded. This solution was then tested with Benedicts and the color was once again recorded. A beaker was filled with enough distilled water to submerge the bag, and it was tested with Lugol’s for starch. This was then tested also for glucose. The bag was then immersed in this beaker of solution. This was left to sit for around 10 minutes, after which it was heated up. The final color was recorded. Then the liquid in the beaker was also tested for glucose and the color was recorded. As opposed the lab manual, the demo done included an extra step in which the bag was heated. Also, a clip was used to keep the tubing from releasing solution out of the ends rather than string.
Lab 1B – Osmosis Lab 1B required six different dialysis tubes that would be filled with varying sucrose solutions. However, due to time constraints, the lab procedure was modified. Instead, every group did two sucrose solutions and a class data chart was made to pool the findings. For our group, 0.4M and 0.6M sucrose solutions were tested. First, we obtained two 10-cm strips of dialysis tubing.
For each tube, we folded up the bottom end and tied it securely so that the solution would not spill. Approximately 15mL of 0.4 sucrose solution was poured into one tube, while 15mL of 0.6 sucrose solution was poured into the other. Using our fingers, we removed most of the air out of the tube, and tied off the other end of the bag with string. Sufficient space was left so that the contents could expand. Both bags were then rinsed off gently with distilled water to remove any sucrose solution spilled. Then the outside of the bags were blotted off and the initial mass of each bag was taken, and recorded in grams. Each bag was placed in a cup that was labeled to indicate molarity of the solution in the dialysis bag. Each cup was filled with enough distilled water for the dialysis tubing to be completely submerged. The cups were left to stand for 20 minutes. At the end of this time, both bags were removed from the water, blotted and weighed again. The mass of each bag was recorded. Unlike the procedure called for in the lab manual, only 10cm of dialysis tubing was used per solution, as opposed to 30cm. Also, each cup was only filled with enough distilled water to cover the tubing, rather than 250 mL or 2/3’s of the …show more content…
cup.
Lab 1C – Water Potential For this exercise, we tested 0.4M sucrose solution as well as 0.6M sucrose solution so the procedure was repeated with each solution.
First, we obtained four carrot sticks per sucrose solution, totaling eight carrots. Each group of carrots was weighted together in order to determine their initial weight. The four carrots for 0.4M sucrose and the four carrots for 0.6M sucrose were weighed separately. Then we poured enough of the assigned solution into each cup so that it would be able to coat the carrots completely, and placed the carrots in the correct cups. The cups were labeled and covered with plastic wrap. Then they were left to stand overnight. In the original lab instructions, potato cores were supposed to be used, and part of the procedure involved cutting the cores. Because baby carrots were used, this step was omitted. Instead of using 100mL of sucrose solution, only enough was used so that the carrots were submerged.
Lab 1D – Calculation of Water Potential from Experimental Data
( ) = –iCRT
a) 0.4M sucrose
( ) =
–iCRT
( ) = (-1)(0.4 mole/liter)(0.0831 liter bar/mole °K)(295 °K)
( ) = - 9.8058 ≈ - 9.81 bars
b) 0.6M sucrose
( ) = –iCRT
( ) = (-1)(0.6 mole/liter)(0.0831 liter bar/mole °K)(295 °K)
( ) = - 14.7087 ≈ - 14.71 bars
SECTION TWO : Results Through the experiments done, it is evident that water flows through a selectively permeable membrane as represented by the carrots and the dialysis tubing from the hypotonic solution to the hypertonic solution.
Table 1.1: Demo
Table 1.2: Dialysis Bag Results – Group Data
Table 1.3: Dialysis Bag Results – Class Data
a) Change in Mass
b) Percent Change in Mass
Graph 1.1: Dialysis Bag Results
a) Individual Data
b) Class Data
Table 1.4: Carrots – Individual Data
Table 1.5: Carrot Results – Class Data
Graph 1.2 – Percent Change in Mass of Carrot Sticks at Different Molarities of Sucrose
a) Individual Data
SECTION ONE: Methods
Lab 1 – Diffusion and Osmosis can be broken down into four parts (A, B, C, and D).
Lab 1A – Diffusion In this exercise, we tested diffusion through dialysis tubing. This was done through a demo with the teacher, rather than individually in groups. First, a piece of 2.5cm dialysis tubing was obtained. Then one end was folded and clipped securely so that a solution poured into the bag would not leak out. Next, the other side of the bag was opened. For step two, a 15% glucose/1% starch solution was tested for the presence of glucose with Benedict’s, and we recorded the data in a table. Using more 15% glucose/1% starch solution, 15 mL was placed in the dialysis bag. The other end was tied, …show more content…
leaving room for the contents in the bag to expand. The color of the contents was recorded. This solution was then tested with Benedicts and the color was once again recorded. A beaker was filled with enough distilled water to submerge the bag, and it was tested with Lugol’s for starch. This was then tested also for glucose. The bag was then immersed in this beaker of solution. This was left to sit for around 10 minutes, after which it was heated up. The final color was recorded. Then the liquid in the beaker was also tested for glucose and the color was recorded. As opposed the lab manual, the demo done included an extra step in which the bag was heated. Also, a clip was used to keep the tubing from releasing solution out of the ends rather than string.
Lab 1B – Osmosis Lab 1B required six different dialysis tubes that would be filled with varying sucrose solutions. However, due to time constraints, the lab procedure was modified. Instead, every group did two sucrose solutions and a class data chart was made to pool the findings. For our group, 0.4M and 0.6M sucrose solutions were tested. First, we obtained two 10-cm strips of dialysis tubing.
For each tube, we folded up the bottom end and tied it securely so that the solution would not spill. Approximately 15mL of 0.4 sucrose solution was poured into one tube, while 15mL of 0.6 sucrose solution was poured into the other. Using our fingers, we removed most of the air out of the tube, and tied off the other end of the bag with string. Sufficient space was left so that the contents could expand. Both bags were then rinsed off gently with distilled water to remove any sucrose solution spilled. Then the outside of the bags were blotted off and the initial mass of each bag was taken, and recorded in grams. Each bag was placed in a cup that was labeled to indicate molarity of the solution in the dialysis bag. Each cup was filled with enough distilled water for the dialysis tubing to be completely submerged. The cups were left to stand for 20 minutes. At the end of this time, both bags were removed from the water, blotted and weighed again. The mass of each bag was recorded. Unlike the procedure called for in the lab manual, only 10cm of dialysis tubing was used per solution, as opposed to 30cm. Also, each cup was only filled with enough distilled water to cover the tubing, rather than 250 mL or 2/3’s of the …show more content…
cup.
Lab 1C – Water Potential For this exercise, we tested 0.4M sucrose solution as well as 0.6M sucrose solution so the procedure was repeated with each solution.
First, we obtained four carrot sticks per sucrose solution, totaling eight carrots. Each group of carrots was weighted together in order to determine their initial weight. The four carrots for 0.4M sucrose and the four carrots for 0.6M sucrose were weighed separately. Then we poured enough of the assigned solution into each cup so that it would be able to coat the carrots completely, and placed the carrots in the correct cups. The cups were labeled and covered with plastic wrap. Then they were left to stand overnight. In the original lab instructions, potato cores were supposed to be used, and part of the procedure involved cutting the cores. Because baby carrots were used, this step was omitted. Instead of using 100mL of sucrose solution, only enough was used so that the carrots were submerged.
Lab 1D – Calculation of Water Potential from Experimental Data
( ) = –iCRT
a) 0.4M sucrose
( ) =
–iCRT
( ) = (-1)(0.4 mole/liter)(0.0831 liter bar/mole °K)(295 °K)
( ) = - 9.8058 ≈ - 9.81 bars
b) 0.6M sucrose
( ) = –iCRT
( ) = (-1)(0.6 mole/liter)(0.0831 liter bar/mole °K)(295 °K)
( ) = - 14.7087 ≈ - 14.71 bars
SECTION TWO : Results Through the experiments done, it is evident that water flows through a selectively permeable membrane as represented by the carrots and the dialysis tubing from the hypotonic solution to the hypertonic solution.
Table 1.1: Demo
Table 1.2: Dialysis Bag Results – Group Data
Table 1.3: Dialysis Bag Results – Class Data
a) Change in Mass
b) Percent Change in Mass
Graph 1.1: Dialysis Bag Results
a) Individual Data
b) Class Data
Table 1.4: Carrots – Individual Data
Table 1.5: Carrot Results – Class Data
Graph 1.2 – Percent Change in Mass of Carrot Sticks at Different Molarities of Sucrose
a) Individual Data