Grade 7 Diffusion Across a Model Cell Membrane Question: Can iodine or corn starch molecules diffuse across a plastic “membrane?” Hypothesis: If the iodine and cornstarch are placed in the same beaker, then the answer can be determined. Materials: Plastic sandwich bag Zip-lock bag Tincture of iodine Cornstarch (2) 500 mL beakers Eyedropper Graduated cylinder Procedure: Fill one beaker with 250 ml of water Add 60 drops of iodine Fill a second beaker with 250 mL of water Add 3 teaspoons of cornstarch and mix well Pour ½ of the starch and water solution into the plastic sandwich bag Make sure that there is NO spilled solution on the outside of the bag Place the bag in the beaker with the iodine/water solution Immediately observe any changes Observe and record …show more content…
The iodine solution is a yellow, the molecules transported through the plastic bag and to the cornstarch. Day Three The color of the iodine is decreasing the iodine molecules diffused with the cornstarch. The cornstarch is darker and settling at the bottom of the bag, separating it from the water. Day Four Iodine solution is clear, with orange specks, and the cornstarch is a dark lavender. The water inside the plastic bag is a light lavender. The iodine molecules diffused with the cornstarch. The colors have changed/decreased. The molecules went from the iodine, through the plastic bag, to the cornstarch. The light lavender is cloudy and the dark lavender is very thick. Analysis: The chart shows the difference in the iodine/water solution and the plastic bag filled with cornstarch processed over the time span of four days. Conclusion: In conclusion, the molecules went from the iodine, through the plastic bag, to the cornstarch. This lab shows that molecules can transport through a material as thick as a plastic bag. Is the hypothesis correct or incorrect? The hypothesis is correct Why is it