self design lab

Pichayut Viwatrujirapong (Earl)

IB Biology SL

IB Self-Design lab

Diffusion of Water in Gummy Bear

Introduction:

Diffusion is the movement of particles from the area of high concentration to the area of low concentration until the concentration reaches the equilibrium point where the concentrations in both areas are equal. In addition to that the diffusion of water is called Osmosis, which is the movement of water across the selectively-permeable membrane, where the water moves from higher water potential or low solute to lower water potential or high solute. For example, if the water potential outside the cell (20% Salts solution outside) is lower than the water potential inside the cell (5% inside) , therefore the water will diffuse out of the cell and cause the cell to shrivel.

Diffusion is very important to cells because it is use to transport material in and out of the cells such as nutrients and waste and if there is not diffusion the cell will not be able to get rid of waste material and get nutrients in therefore the cells will die. For example, if there is higher concentration of Carbon Dioxide inside the cell more than outside the cell and the cell wanted to get rid of Carbon Dioxide in its cell therefore the cell uses diffusion to transport Carbon Dioxide out of the cell by moving it down the concentration gradient.

In this investigation, the rate of diffusion in Gummy Bear (symbolize as cells and the Gummy bear skin symbolize the cell membrane therefore the material will diffuse in and out of Gummy bear) in the different temperatures will be investigated. The Gummy bear will be place in three different containers which will be fill with saturated salt solution in three different temperatures condition, one in warm temperature, one room in temperature , and one in cold temperature. As a result of this, the effect of the temperature on the rate of diffusion will be reveal.

Hypothesis:

The Gummy Bear in the highest temperature saturated salt solution will shirk the most, because the salt solution will diffuse out of the Gummy Bear quickest. On the other side, the Gummy Bear in the lowest temperature salt solution will shrink least because the salt solution will diffuse out of the Gummy Bear slowest, and the Gummy Bear in the room temperature will shrink a little bit.

Design:

Research Question:

What is the effect of the temperature on the rate of diffusion in the Gummy Bear?

What is the effect of temperature on the rate of diffusion in a Gummy Bear?

Variables:

The dependent variable is the rate of diffusion in the Gummy Bear and the independent variable is the temperature of the saturated salt solution. In addition to that there are several controlled variables that were kept constant throughout the investigation are the length of the Gummy Bear, the concentration of the saturated salt solution , color of the gummy bear, and the temperature of the solution. The temperature of the solution was kept constant to make sure the diffusion rate of the certain temperature was constant. The size, color, and the length are kept same in order to keep the rate of diffusion constant too. The temperature (measure by using thermometer) in lower temperature condition is controlled by the temperature of the freezer adjustment in the refrigerator, and the water in the higher temperature condition is controlled by the water bath, and the temperature in the room temperature condition is controlled by putting it in the cupboard which it will not be affected by the air condition but it is hard to keep the temperature constant therefore this made it as the weakness of the experimental design. In addition to that the same color, same amount of concentration of the saturated salt solution (by mixing it in the same amount of concentration 10% = 900 ml of water with 90 grams of salt and pour 300 ml if saturated salt solution in three 500 ml beakers) and choose the closet length and size Gummy Bear (by measuring it by using ruler and electronic balance) were used for all trails also to keep constant.

Material:

3 – 500 ml beakers

12- Gummy Bears: 4 for each color – red, white, yellow, and green

900 ml - water

90 grams - salt

1 - Ruler

1 - Electronic Balance

1 - Water Bath

1 – Refrigerator

3 – Thermometers

15 – Ice cubes

Procedure:

1) Measure the length and weight of gummy bear using ruler and electronic balance2) Fill up 3 500ml beakers with 300 ml of 10% salt saturated solution in to each beakers3) Heat up one beaker by putting it in the water bath, put ice in one beaker and put it in

refrigerator, and left the last beaker in the room temperature condition which is in the cupboard and measure these beaker temperature. The water bath, refrigerator, and cupboard help to keep the temperature constant.

4) Measure the temperature of the three saturated salt solution until the temperature reaches 55 °C, 25 °C and 3 °C.

5) Put in 4 gummy bears into each beaker – red , white , yellow, and green6) Left it for 3 hours and 50 minutes. 7) Measure and record the volume and the length of the gummy bear8) Calculate uncertainties and the increase or decrease of size of the gummy bear. 9) If have time repeat this experiment one more time to improve the precision.

Data Collection and processing:

Data Table

Table 1: Beaker 1 (higher temperature solution) - Original size and length and Color of the Gummy Bear before putting into the salt solution

Color of the Gummy Bear Mass of the Gummy Bear(±0.01 grams)

Length of the Gummy Bear(±0.1 mm)

Green 2.24 20Yellow 2.34 20

Red 2.35 19.8White 2.35 20

Table 2: Beaker 2 (room temperature solution) - Original size and length and Color of the Gummy Bear before putting into the salt solution

Color of the Gummy Bear Mass of the Gummy Bear (±0.01 grams)

Length of the Gummy Bear (±0.1 mm)


Red 2.34 18White 2.32 19

Table 3: Beaker 3 (lower temperature solution) - Original size and length and Color of the Gummy Bear before putting into the salt solution

Color of the Gummy Bear Mass of the Gummy Bear (±0.01 grams)

Length of the Gummy Bear (±0.1 mm)


Red 2.32 20White 2.33 19

Table 4: Beaker 1 (higher temperature solution) –size and length and Color of the Gummy Bear after put in the saturated salt solution for 3 hours and 50 minutes



Green - (dissolved) - (dissolved)Yellow - (dissolved) - (dissolved)

Red - (dissolved) - (dissolved)White - (dissolved) - (dissolved)

Table 5: Beaker 2 (room temperature solution) –size and length and Color of the Gummy Bear after put in the saturated salt solution for 3 hours and 50 minutes



Green 2.12 17.5Yellow 1.98 18

Red 2.14 17.5White 2.16 18.5

Table 6: Beaker 3 (lowest temperature solution) –size and length and Color of the Gummy Bear after put in the saturated salt solution for 3 hours and 50 minutes




Red 2.19 20White 2.17 19

Table 6: Average of size and length and Color of the Gummy Bear before and after put in the saturated salt solution for 3 hours and 50 minutes

Beaker Average Mean of Mass of the Gummy Bear before put in

the solution(grams)

Average Mean of Length of the Gummy Bear

before put in the solution

(mm)

Average Mean of Mass of the Gummy Bear

after put in the solution(grams)

Average Mean of Length of the

Gummy Bear after put in the

solution(mm)

Beaker 1 (Hotter temperature)

2.32±.055 19.95±0.1 - (dissolved) - (dissolved)

Beaker 2 (Room temperature)

2.32±.04 18.5±0.5 2.1±.09 17.88±0.5

Beaker 3 (Lower temperature)

2.33±0.1 19.5±0.5 2.2±0.3 19.5±0.5

Table: 7: The average of the decrease of in the mass and the length of the Gummy Bear

Beaker Average Mean of Mass of the Gummy Bear decrease by

(grams)

Average Mean of Length of the Gummy Bear decrease by

(mm) Beaker 1 (Hotter temperature) 2.32±.055 19.95±0.1Beaker 2 (Room temperature) 0.22±.13 0.62±.1Beaker 3 (Lower temperature) 0.13±.04 0 (stay the same length)

Sample calculation:

i) Mean of mass/length of the gummy bear:

= (Mass 1 + Mass 2 + Mass 3 +Mass 4) / 4

= (2.24-2.34+2.35+2.35) / 4

= 2.32 grams

ii) Uncertainty of mean mass/length of the gummy bear

= Range / 2

= (20 – 19.8) / 2

= ±0.1 grams

Graphs :

Average rage of mass loss in each beakers:

Average of length loss in each beaker:

Conclusion and Evaluation:

According to these results, the results show that as the temperature increases the faster the diffusion is , because if compared the average of the decrease in mean of mass of the Gummy Bear and the average of the decrease in mean of mass of the Gummy Bear the higher temperature is the one that have the biggest mass and length lost , that its mass decreased by 2.32±.055 grams and its length

decreased by 19.95±0.1 mm. In addition to that comparing literature value graph and with the experimental graph these graph shows the same result which is the higher the temperature the higher the rate of diffusion.

Evaluation

One of the big error in the design of the method is that the method of measuring the amount of water and the amount of salt, because in this investigation the measurement of 900 ml of water was done by using the 500 ml beaker and it is not accurate way of measuring the amount of water therefore to improve this we could use a more precise scale which use a measuring cylinder of 100ml instead of 500 ml beaker and in addition to that when we are measuring the amount of salt we cannot get the exact 90 grams of salt because the measuring scale is only in the hundredth scales and to improve this precision on the next experiment we could use the thousands scales electric balance instead using hundredth scale balance.

One of the big problem in the carrying out the experiment are that the time management problem that in the investigation the timing was not that good and therefore it made the results seem to be unclear for example the higher temperature beaker because it is still a mystery when did the Gummy Bear dissolved in the salt solution substance, but to fix this problem next time in the investigation a person should check out the Gummy Bear every 10 minutes and it would make the result more precise and clearer too. Not only that the data is not that accurate too because in this investigation there is no result of the higher temperature beaker gummy bear of the higher temperature beaker because the Gummy Bears dissolved in the saturated salt solution. The significance of each of the weaknesses on the results is that it made the results seem to be unclear and not precise and accurate. Lastly if there is more time to do this investigation doing more trails would definitely improve this investigation results for sure.

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