MCQ Detailed View

In volumetric analysis, indicators are substances that change color at or near the equivalence point of a titration. The choice of an indicator depends on the type of acid and base involved. Methyl orange is a commonly used indicator for acid-base titrations, particularly when the acid is strong.

Methyl orange changes color from red in acidic solution to yellow in basic solution. The color change occurs over a pH range of 3.1 to 4.4, which makes it suitable for titrations where the equivalence point is in this acidic region. Strong acids completely dissociate in water, producing a low pH, which matches the effective color change range of methyl orange.

It is especially suitable for titrations between a strong acid and a weak base, because the equivalence point occurs at a pH less than 7. Using methyl orange in such titrations ensures a clear, sharp endpoint that students and chemists can observe easily.

Methyl orange is not suitable for titrations involving strong acid with strong base if the goal is neutral equivalence, because other indicators like phenolphthalein would provide a better color change around pH 7. It is also unsuitable for weak acid-strong base titrations, as the endpoint occurs at higher pH values outside its effective range.

Understanding which indicator to use is essential in volumetric analysis to achieve accurate results. Selecting methyl orange when the acid is strong ensures precise detection of the equivalence point and reliable determination of concentrations in analytical chemistry experiments.