Bromocresol Green

[cmwatson78]

I need to know how much of a difference there is between Bromocresol Green .1% and Bromocresol Green .2%. How much does it matter. I know it indicates a differnce of .2 in pH, but does that really matter? I am titrating phosphate with sulfuric acid using Bromocresol Green as the indictor. And I need to know what I should order.

 

[kenvlach]

By .1%, do you mean 0.1%? If so, write it correctly.
By .2%, do you mean 0.2%? If so, write it correctly.

Re "it indicates a differnce of .2 [sic] in pH."
Wrong, the 0.2% indicator is easier to see. Use twice as many drops if using 0.1% indicator instead (or half as many if vice versa). It changes color at about pH 4.5.

I would order a pH meter with a combination electrode & pH 4 & 7 standards.

If you really must go by color change [no electricity?], both Fisher Sci. & Spectrum sell 0.1% bromocresol green in 500mL poly bottles for $25. & S&H + tax if applicable. Or, if using lots & lots, order the reagent powder and some isopropanol to dissolve it in (unless buying the water-soluble salt form).

http://www.fishersci.com

http://www.spectrumchemical.com