Chemical Forums

Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: znaes97 on January 29, 2025, 12:22:22 PM

Title: 1% w/v vs. 0.04% w/v Bromophenol Blue Indicator
Post by: znaes97 on January 29, 2025, 12:22:22 PM

Hello,
I have to prepare for the following titration:

Free Acid: Pipet a 2 milliliter sample of the solution into a 150 milliliter beaker, add 3 to 4 drops of bromphenol blue indicator, then titrate using a 0.1 N sodium hydroxide from a green color to a purple color. The normal amount of 0.1 N sodium hydroxide required to make the color change is 2.0 to 2.2 milliliters.

Our lab chem supplier has 1% w/v and 0.04% w/v bromo blue. Which of these two is the 'standard' bromo blue concentration/which would be better for this titration? Thanks in advance

Title: Re: 1% w/v vs. 0.04% w/v Bromophenol Blue Indicator
Post by: Hunter2 on January 29, 2025, 12:50:01 PM

Try and error. At least you have to see the clear colour change. I would use the more diluted one. If not enough can add some Drops more.