The Rate of Diffusion Essay

Abstract

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.

Introduction

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 __________.

Results

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).

Read also  Cell Transport Mechanisms and Permeability

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 .93

1.01 .89 .76 .96

1.05 2.06 .83 1.01

1.60 2.21 1.14 1.02

1.12 1.25 1.03

1.12 1.42 1.05

1.33 1.12

1.39 1.19

1.42 1.30

1.43 1.34

1.47 1.45

1.52

1.56

1.61

1.64

1.75

1.78

Total Average weight gain 1.05

overall 0.83 0.57 0.98

Each group’s change in weight of each of the dialysis bags in the different types of water.

Discussion

The data seems to agree with me in the fact that the rate of diffusion was the quickest in the room temperature water. My partner’s and my experiments average was 1.085 grams with the ice water and 1.53 with the room temperature water. This shows that the rate of diffusion was faster in the room temperature water, but not by much; it only had 0.445 grams more than the bags that were in ice water. In the class’s experiments, the bags in room temperature water only weighed 0.07 grams more than the bags in ice water. The bags in the 47-49° C range came as third fastest, leaving 59-60° C range dead last. They varied by 0.26 grams.

Overall the rate of diffusion didn’t make a huge jump in any certain temperature change in the water. It changed slightly, but not enough to make quite an impact on the process. This data also shows that there wasn’t much change overall between room temperature water, ice water, and the 47-49° C water. The problem with this data is the class chart. It seems as though overall people messed up in very common ways. Some of the data were in the negative which probably means they either didn’t tie the dialysis bag tight enough or poked a whole in the bag. Also, some people didn’t have enough time to complete the experiment at the correct interval time.

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