I am wondering what could cause my litmus paper to first react to the alkaline. turning blue, and then changing to an acidic red color?
Litmus paper contains a pH indicator, which is a compound that changes color in the presence of acid or base. Natural litmus contains numerous pH-sensitive dyes, but most of them are based on the 7-hydroxyphenoxazone core. In the presence of acid, the imine nitrogen is protonated; in base, the phenolic oxygen is deprotonated. These reactions are reversible, so the color will change when the pH is changed.