Science Buddies: "Ask an Expert"

Hi Science Expert,

I am conducting a group science project through Innovation Nation and we had a couple of questions regarding the basis of our project. In one experiment we are depicting simply how diffusion can be affected by the temperature of the substance it is entering. In our experiment we are taking 2 glasses with the same amount of water, but one is hot and the other cold, and dropping dye into it to observe the rate of dye diffusion.

Our question is: What do you think is the best way to gage the amount of diffused dye over a span of 30 seconds for 5 minutes? Our procedure suggests recording rounded percentages (10%, 20%, 30%, etc.) every 30 seconds, but we weren't sure if this was the most effective method. Thank you.

Hello,
This is a great question. When it says use a percentage...the instructions refer to your best guess as to how much of the dye has diffused. If you do this I would suggest doing the cold and hot water at the same time so you can compare the rate of diffusion between them.

Another possible option is to dip strips of white paper into the water. The dye will absorb into it and then you can do a side by side comparison of the strips. This would give you something a little more concrete to look at and compare. You could create a gradient before you start your experiement that you label 0-10, where 0 is no dye added ad 10 is the maximum amount of dye added. You could create the gradients 2-9 by slowly adding more and more dye to your water and putting in test strips until you get to the maximum amount (10). Then as you do your experiment you can determine which level gradient you have (0-10)for each aspect that you are testing. Just make sure that if you let your sample strips dry, that you let you test strips dry too so that you are doing a fair comparison. In order to gauge diffusion you would want to have specific distance spots where you would test the water with a strip from where you add the dye. It might be easier if you do it in something that has a larger surface area for the dye to travel horizontally so you can space out your test strips such as a bowl or even a baking dish that you make cake in. If you add the dye on one end of the dish you can measure out testing spots every 1 (inch/cm or whatever that makes for your size container) away from the dye. Test these same spots for every time interval you measure. What you should see is that with more time, the test strips will contain more and more dye.

Good luck!

Hi Katie,

Thank you so much for your response, you have been a big help to our project.