Question

Addition of the indicator methyl orange to an unknown solution leads to a yellow color. The addition of bromthymol blue to the same solution also leads to a yellow color. (a) Is the solution acidic, neutral, or basic?

Answer 1

Answer: The solution is acidic.

Explanation:

You must find the behavior of the different indicators in the literature, for which you can use internet.

There you will find that methyl orange is useful to differentiate if a solution is more acidic (pH below 3.1) or less acidic (pH above 4.4).

In other words, when acidity in decreasing, i.e. the pH is increasing, the methyl orange indicator goes from red (more acidic) to yellow (less acidic).

So, as it is stated that the addition of the indicator methyl orange to the unknown solution leads to a yellow color, you just can tell that the pH is above 4.1, which means that the solution may be slightly acid, neutral or basic. In this case, the indicator methyl orange cannot help you to determine the answser.

So, you must move to the information regarding the other indicator (bromthymol blue) to try to infer whether the solution is acidic, neutral, or basic.

You can find in the literature that the indicator bromthymol blue leads to a yellow color in acidic solutions, greenish in neutral solutions, and blue in basic solutions.

Since it is stated in the question that the adition of bromthymol blue to the same solution also leads to a yellow color, you can conclude that the solution is acidic.