I have an unknown substance dissolved in water, and it's milky white. When I put in a pH paper, the paper shows that it is slightly basic at pH ~8. However, after putting in the pH paper, the solution changed color from milky white to a very faint blue. What possible compound could this be?
What about the volume of the analyzed mixture? I doubt that anyone can guess what the substance is, but my guess about the color is that the indicators on the pH paper might have been partially dissolved in the mixture. And, since the color of litmus paper at a pH = 8 is blue, it could be a possible explanation for the color, especially if you are dealing with a small volume of liquid.