Lab Report
Question: How does osmosis work?
Statement: If you place a hypertonic dialysis bag into a beaker that is hypotonic, then the
hypotonic side moves toward the hypertonic side, because the distilled water can move into
the bag but the distilled water inside the bag cannot move out, for the reason of the sucrose
molecules being larger than the water molecules and blocking them from going out.
Materials:










4 15-cm length of dialysis tubing, soaking in dH2o
8 10-cm pieces of string
Ring stand and funnel apparatus
52mL graduated cylinder
U small string tags
China marker
4 400 mL beakers
Dishpan half-filled
Paper toweling
Balance
Procedure:
1. Obtain four section of dialysis tubing that have been presoaked in distilled water.
2. Fold over one end of each tube and tie it tightly with string.
3. Slip the open end of the bag over the stem of a funnel. Using the graduated cylinder to
measure volume, fill bas as follows.
10 mL of distilled water
10mL of 15% sucrose
10mL of 30% sucrose
10mL of distilled water
4. Fold the end of the bag and tie it securely with another piece of string.
5. Rinse each filled bag in the dishpan containing distilled water; gently blot off the excess
water with paper toweling
6. Weigh each bag to the nearest 0.5 g.
7. Record the weights in the column marked “0 min” on the table
8. Number four 400 mL beakers with a china marker.
9. Add 200 mL of H20 to beakers 1-3in the correspondingly numbered beakers.
10. Place bag 4 in the beaker containing 30% sucrose
11. After 20 min. remove each bag from its beakers immediately after weighing.
At the end of the experiment, take the bags to the sink, cut them open, pour the contents down
the drain and discard the bags in the wastebasket. Pour the contents of the beakers down the
drain and wash them according to the instructions given on the page x.
No.
Bag 1
Bag 2
Bag 3
Bag 4
Bag
contents/beaker
contents
Distilled water/
distilled water
15%
sucrose/
distilled water
30%
sucrose/
distilled water
Distilled water/
30% sucrose
0 min.
10 min.
30 min.
10.5 g.
12.3 g.
11.9 g.
Weight
changes
(grams)
-1.4 g.
11.6 g.
10.4 g.
8.9 g.
2.7 g.
11.3 g.
12.4 g.
11.7 g.
-0.4 g.
10.2 g.
9.4 g.
3.9 g.
6.4 g.
What was the direction of net movement of water in bags 2 to 4 into or out of the bags?
The direction of net movement of the water in bags 2 to 4 was, the hypotonic moved
into the hypertonic side.
Witch bag Gained the most weight and why?
Bag 4 gained the most weight, because the water in the hypotonic side moved into the
bag witch was the hypertonic side to gain more weight in the bag.
Conclusion;
We accepted our hypothesis because when we did the experiment that was what really
happened
We started with four dialysis tubing’s, tied one end of each, and opened the other end. Then we
put distilled water in the first one, 15% sucrose in the second one, 30% sucrose in the third one and
distilled water in the last one. They were all put in their own beaker, the first three in distilled water and
the last in 30% sucrose. We observer the distilled water in the distilled water from the first time we
weighed it to the last, it changed -1.4 grams. The 15% sucrose in distilled water changed 2.7 grams. The
30% sucrose in distilled water changed -0.4 grams. Finally, the distilled water in 30% sucrose changed
6.4 grams. In conclusion, the reasons for this change is that the sucrose molecules are too large to fit
through the bags, the distilled water can come into the bags but not leave very easily.
Errors we could have made…

Not tying the dialysis bags correctly

Not having the right amount of water or sucrose solution