Science Buddies: "Ask an Expert"

I saw Science Buddies' project about testing if how chicks can breathe inside their shell. I want to do this project. But am curious when the instructions tell me to mix dishwash detergent with blue dye in water, what is the purpose of detergent? I have not been able to find any answers as to WHY. Can someone help explain? Thank you.

[Moderator note: Project appears here: https://www.sciencebuddies.org/science- ... p046.shtml]

Hi nvue,

That is a very interesting question! To be honest, I'm not entirely sure what role the detergent plays in this project. But, I have a couple of ideas. Before getting to those ideas, however, I wanted to mention that you could do an experiment to find out the role dish soap plays in this experiment. You could do one round of the experiment following the procedure exactly as written. You could then do the experiment a second time, this time leaving the dish soap out of the water-dye mixture. Then, you could compare the shells from these two experiments. How are they different? How are they similar? If everything except the presence or absence of dish soap is the same, then the differences you observe will tell you about what the dish soap does during the experiment. You could present that as part of your science project!

Now, I can think of a couple of things the dish soap may be doing. Dish soap contains surfactants, which are chemicals that have one end that likes water and another end that likes oils. Surfactants decrease the surface tension of water. They also help to break down some kinds of chemicals because of their dual-sided nature. The surfactants in dish soap, for example, are really good at taking greasy things and breaking them down into lots of little packets of grease surrounded by surfactant; that's why you can use dish soap to wash grease off pots and pans. I suspect that the surfactants in the dish soap interact with the dye molecules to help the dye "make it" through the egg shell. But, I'm not 100% certain that is the case. You could test that hypothesis by doing the experiment I suggested in the first paragraph. Let me know if you decide to do the experiment; I'd love to know what you find out!

All the best,
Terik

Thanks for your reply and suggestion. The background info on surfectants is interesting. Not sure yet on what idea/project I will work on... but if this is the one, I will let you know! Thanks again.

Hello nvue,
Thanks for your question and for posting. I'm wondering if you saw that there is a technical note at the bottom of the page that explains WHY the detergent is used: https://www.sciencebuddies.org/science- ... #procedure. Did you have questions after reading that or were you confused by any part of that? We can certainly help answer those questions here. I look forward to what you finally decide on for your project.
If you are uncertain about what you want to do, check out the Science Buddies project wizard, where you can enter an area of interest, such as biology, and it will produce a list of project ideas for you: https://www.sciencebuddies.org/science- ... ndaproject, or browse by topic: https://www.sciencebuddies.org/science- ... llprojects.
I look forward to hearing from you soon!