What is the color of bromcresol green indicator in a solution with a pH value of 2.0?
(1) blue
(2) green
(3) red
(4) yellow
Answer: Choice 4
Solution: An indicator allows us to figure out the pH range of the solution and whether it is acidic or basic. To do this problem, we need to look at Table M of the Regent Reference Table, Common Acid–Base Indicators.
According to the table, bromcresol green, has a pH range for color change of 3.8-5.4 and the color change is yellow to blue. Therefore, a solution whose pH is less than 3.8 will have a yellow color with bromcresol green indicator. On the other hand, a solution whose pH is higher than 5.4 will have a blue color.
In this question, the pH value is 2.0, which is less than 3.8, therefore bromcresol green will be of yellow color.