How the Rate of Diffusion is Affected by the Temperature of Water

Topics: Osmosis, Semipermeable membrane, Diffusion Pages: 6 (924 words) Published: August 23, 2004

I found that this experiment gives me an understanding on how osmosis and

diffusion works. In its simplicity, it explains the process that our bodies (mainly cells)

use all the time. It also showed me that even with the temperature changing, it doesn't

drastically change the rate of diffusion.


Diffusion is important in all living systems. Osmosis is the passage of water from a region of high water concentration through a semi-permeable membrane to a region of low water concentration (Purchon 1). Diffusion is the movement of a substance from an area of high concentration to low concentration (Biological 21).

With this knowledge we tried to recreate diffusion for students to understand the process. The dialysis bags represented our selectively permeable membrane with the fluid inside it, sucrose. How much of the substance moves from the cup to the bag quickly depends on the temperature of the substance. The class used four different temperatures to measure the rate of diffusion.

I thought that the rate of diffusion would increase as temperature increased because the more heat put into the process the quicker the molecules will move.

The null hypothesis is that no matter what the temperature is the rate of diffusion will stay the same.

Materials and Methods

The materials used were a dialysis bag, string, pipet, beaker with water, 10% sucrose water, and a balance. The variables that we made standardized were the concentration of the solute, length of the dialysis bags, and time.

Each group poured 10 milliliters of 10% sucrose into two 15 cm long dialysis bags and bent the end of the bags and tied them. Then the bags were immersed in water, dried, and measured. Next the bags were put into room temperature (about 20°C), 60° C, 45°C, or ice water (0°C). Each group measured the bags three more times at 10 minute intervals drying them off each time. Once they finished, each group subtracted the final measurement from the initial to see how quickly the water diffused into or out of the bag. My partner and I did the experiment twice, once with ice water and the next in room temperature water. We had two dialysis bags for each of the two experiments that we did.

The independent variable is ______________. The dependent variable is __________.


The first two tables are the information that my partner and I got through our two experiments. The data from our experiments show that the rate of diffusion was faster with the room temperature water. The last table shows the class's data. The class's results show that the rate of diffusion occurs the fastest in room temperature water.

Both my data and the rest of the class's data show that the rate of diffusion is fastest in room temperature water. The overall total weights of the dialysis bags immersed in room temperature water weighed the most which shows the rate of diffusion being the fastest in those experiments.

Table 1 & Graph 1: The Change in weight of the 2 diallysis bags of 10 ml of 10% sucrose left in ice water (2°C).

Time in minutes Weight of 1st bag in grams Weight of 2nd bag in grams

0 10.93 10.89

10 11.49 11.28

20 11.76 11.66

30 12.05 11.94

Total weight gained in each bag 1.12 1.05

Table & Graph 2: The change in weight in the 2 dialysis bags of 10ml of 10% sucrose left in room temperature water (21°C).

Time in minutes Weight of 1st bag in grams Weight of 2nd bag in grams

0 10.92 10.92

10 11.56 11.45

20 12.08 11.90

30 12.56 12.35

Total weight gained in each bag 1.64 1.43

The change in weight in the 2 dialysis bags of 10ml of 10% sucrose left in room temperature water (21°C).

Table & Graph 3: Each group's change in weight of each of the dialysis bags in the different types of water.

21-23° C Room Temperature 47-49° C 59-60° C 2° C ice water

-1.77 .03 -0.30 .24

.16 .20 -0.38 .61

.34 .28 .06 .76

.35 .40 .16 .77

.42 .68 .56 .88

.76 .73 .75...
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