What colour does screened methyl orange indicator turn when in 1) alkali 2) acid and 3) neutral?
Screened methyl orange is ordinary methyl orange to which a blue dye, xylene cyanole, has been added. The idea is to shift the colours into another part of the spectrum to tackle the problem some people have with partial colour-blindness affecting their perception of red and yellow. The acid colour becomes purple, the alkali colour becomes green, and the equivalence colour is a sort of muddy grey colour in between (this is not neutral because the pKa of methyl orange is 3.7). Personally, I have never thought this reasoning very satisfactory because the eye is still relying on the distinction between red and yellow. In any case I have yet to meet anyone who has trouble with methyl orange but finds screened methyl orange acceptable! Ulex Risk assessment Before attempting any practical work based on the advice and suggestions on this website, you must do the following. Identify any hazards, assess the risks from these hazards, and then decide appropriate control measures to reduce the ris
