What causes Phenol Red dye to change color?

Question

We did this lab in school, where we put yeast+sugar, boiled yeast, dry seeds, sprouted seeds, a live cricket, a dead cricket, vinegar, seltzer, and our breath on Phenol Red dye solution. The yeast+sugar, sprouted seeds, live cricket, vingar, seltzer, and our breath caused the dye to change color (to a yellow or orange).

But I'm not sure what substance in each of these things caused the dye to change color.

Because then we also put the vinegar, seltzer, and our breath on some limewater. But only the seltzer and our breath caused it to turn foggy. I know limewater is an indicator for carbon dioxide, but I dont know what phenol red dye is an indicator for. And I don't know why the vinegar didnt react.

Can someone help me? Can someone explain it in simply, because I searched for the answer and the websites I got were too complicated.

Answer 1

phenol red is a pH indicator. It tells you if the substance is an acid or a base. It turns yellow in acidic conditions. So if carbon dioxide is being produced that carbon dioxide mixes with water to form carbonic acid and the pH of the solution becomes more acidic. It reacts to the availability of the H+ ions in the solution. The more H+ ions the more acidic the solution. The fewer ions the more basic the solution.

Answer 2

Try wikipedia! everyone else does, It may not be right, but it is there!