Methyl orange used as an indicator in titrations is ______ on the alkaline side and _______ on the acid side.

Methyl orange used as an indicator in titrations is ______ on the alkaline side and _______ on the acid side.

• A. Colorless, Orange
• B. Orange, Red
• C. Reddish-Orange, Reddish-Purple
• D. Yellow, Salmon Pink

Answer: (D)

Color depends on pH for methyl orange. In basic or alkaline solutions it appears yellow, while in acidic solutions it shifts to a reddish-pink color (salmon pink). This happens because the indicator exists in two forms: the deprotonated form is yellow, and the protonated form is red/pink. The transition between these forms occurs around pH 3.1–4.4, so the acid side shows the pink shade and the alkaline side shows yellow.

Color depends on pH for methyl orange. In basic or alkaline solutions it appears yellow, while in acidic solutions it shifts to a reddish-pink color (salmon pink). This happens because the indicator exists in two forms: the deprotonated form is yellow, and the protonated form is red/pink. The transition between these forms occurs around pH 3.1–4.4, so the acid side shows the pink shade and the alkaline side shows yellow.