When electricity is passed through a pickle, it is conducted through Na+ and the Cl- ions that are present in the pickle. The electricity excites the electrons to a higher energy state, and when the fall back to ground state they emit a yellow/orange light.
Universal indicator goes from red (pH 4) to violet (pH10) as the pH of a substance changes. Adding NaOH to water starts the solution off at pH 8-9 (blue). When dry ice is added to water it forms carbonic acid, and lowers the pH, which is the reason for the color changes. The “fog” that we see is condensed water vapor though, not carbon dioxide gas.
This demo uses acid base chemistry and an indicator to make an ink that will appear or disappear depending on the solution added to it. Phenolphthalein, which is clear, reacts with a base, and then turns pink.
This demo decomposes ammonium dichromate using a fuse soaked in ethanol. The reaction is a violent one, that resembles a volcano. Ammonium dichromate is an orange solid, while chromium (III) oxide is a dark green solid.
(NH4)2Cr2O7(s) → Cr2O3(s) + N2(g) + 4H2O(g)
When different ionic compounds are heated, electrons around the metal atom become excited and jump energy levels. When the electrons fall back to ground state they release light and heat energy. The amount of energy released determined the wavelength and color of the light released, resulting in different colored flames.
Under basic conditions glucose is oxidized while methylene blue is reduced, changing from blue to colorless. The reduction reaction can be reversed by shaking the flask which forces oxygen into solution, which oxidizes the methylene blue, thus turning it back to blue. If the flask is let sit, the oxygen will come out of solution making the solution colorless and ready to shake again.
When sugar is reacted with concentrated sulfuric acid it creates a black foam made of elemental carbon. The water that is produced in the reaction is gaseous and causes the foam to rise.
H2SO4 + C12H22O11 → 12C + 11H2O + a mixture of acid and water