Describe the change of color of methyl orange in acid and base solution.  

Expert Answers
gsenviro eNotes educator| Certified Educator

Methyl orange is one of the most commonly used color change indicator in acid-base titrations. The purpose of color change indicator, in such titrations, is to change the color of the solution as the pH of the solution changes. The chemical formula of methyl orange is `C_14H_14N_3NaO_3S` . This indicator has a yellow color in alkaline solutions and red color in acidic solution. In between, it transitions to orange color. 

More specifically, the color change takes place at a pH of 3.7. At a pH of 3.1 or less, methyl orange is red in color. As we continue adding alkaline solution, the pH of the solution rises and between a pH of 3.1 and 4.4, the color of the indicator is orange. With continued alkali addition, the pH rises and above a pH of 4.4, methyl orange appears yellow.

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