What is the colour of #"methyl orange"# in basic solution?

2 Answers
anor277
Mar 28, 2016

It should be bright yellow.

Explanation:

Methyl orange has a #pK_a = 3.47#. In aqueous solution the indicator should be bright yellow in colour at #pH# #># #4#..

Stefan V.
Mar 29, 2016

Bright yellow.

Explanation:

Methyl orange is a pH indicator that is red in acidic medium and yellow in alkali medium.

More specifically, methyl orange is red in solutions that have a pH that's lower than #3.1# and yellow in solutions that have a pH that's higher than #4.4#.

http://fineartamerica.com/products/methyl-orange-indicator-andrew-lambert-photography-greeting-card.html

Since potassium hydroxide, #"KOH"#, is a strong base, the pH of the solution will be higher than #7#, which of course implies that adding methyl orange to the solution would change its color to bright yellow.

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