what is the color of phenol red at an acid ph
Phenol red A solution of phenol red is used as a pH indicator, often in cell culture. Its color exhibits a gradual transition from yellow (λmax = 443 nm[2]) to red (λmax = 570 nm[3]) over the pH range 6.8 to 8.2. Above pH 8.2, phenol red turns a bright pink (fuchsia) color.[4][5]
Universal indicator The colours from yellow to red indicate an acidic solution, colours blue to violet indicate bases and green colour indicates that a solution is neutral.