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

Mar 28, 2016

It should be bright yellow.

#### Explanation:

Methyl orange has a $p {K}_{a} = 3.47$. In aqueous solution the indicator should be bright yellow in colour at $p H$ $>$ $4$..

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 $4.4$.

Since potassium hydroxide, $\text{KOH}$, 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.