| MadSci Network: Chemistry |
Message: Mad Scientists: My students did the following activity and came up with some hypotheses. Would you please comment.Sounds good. The CO2 bubbles move through the water, causing everything around them (like water molecules and dye particles) to move all over the place in a chaotic fashion.We had three cups of water.One cup of salt water,one cup of plain water, and bubbley water and put two drops of blue food coloring in each one. Ryan Kettner age 8
The bubbly water is blue first because the bubbles spread the food coloring. Ryan Erickson age 8
If you made plain water bubble by boiling it, the dye would also mix in much faster.
The salt water is like a shield and holds the food coloring for awhile.Cody Law age 8 1/2Right again! The particles created when salt dissolves form a sort of shield that makes it hard for the food coloring to move around (imagine if the class stood together in a group and held hands, while one person tried to free himself and move around the middle).
The plain water does not have bubbles to move or salt to hold it so the color just drops down. Brittany Huber age 7 1/2There you go. On the molecular level, the molecules are attached to each other, but there's enough space for the dye molecules to drop down undisturbed.
Hope this helps (and was neither too simplistic nor too technical)
Amanda Kahn