Bromo Cresol Green is a pH indicator. How do we make a solution from its powder form ?

Answer 1

Indicator name:-3',3",5',5" - Tetrabromo - m - cresol - sulfonephthalein (Bromocresol Green)
pH range:-3.8 - 5.4
Colour change:- yellow to blue
Preparation:- 0.1 gm in 14.3 ml 0.01 M NaOH + 235.7 ml water

Buddy I got another one, But I don't know whether that will help you or not,

Preparation of 2.0% bromocresol Green in a stable solvent combination is obtained as follows:

(1) 35 ml (2%) of propan-2-of was added to 1750 ml of silicone oil (20 mm.sup.2/ s and stirred well. The solution is left for 3 minutes and a clear colorless solution was obtained.

(2) 35 ml of bromocresol green was added to the mixture and stirred.

(3) The mixture is indirectly heated in a water bath. The temperature of the water bath did not exceed 100.degree. C. The mixture was left in the water bath for 10 to 12 minutes with continuous stirring. This enhances the indicator solubility.

(4) The mixture was removed from the water bath and left to cool down to room temperature. A clear yellow solution was obtained by the end of this step.

This indicator works on paper pads which have been treated with sodium hydroxide and changes color from yellow to blue.


Preparation of a mixture of two pH indicators

A mixture of bromocresol green in silicone oil 20 mm.sup.2 /s and methyl red in silicone oil 20 mm.sup.2/ s at the ratio 1:1 was produced as follows:

5a. Preparation of bromocresol green combination:

(1) 17.5 ml of propan-2-of were added to 900 ml of silicone oil 20 mm.sup.2/ s and stirred well. The mixture was stirred for 3 minutes. A clear colorless solution was obtained.

(2) 17.5 ml of bromocresol green were added to the mixture obtained from step 1 and stirred well.

(3) The temperature of the water bath did not exceed 100.degree. C. The mixture was left in the water bath for 10 to 12 minutes with continuous stirring. This enhances the indicator solubility.

(4) The mixture was removed from the water bath and left to cool down to room temperature. A clear yellow solution was obtained by the end of this step.


Preparation of mixture of phenolphthalein and bromocresol green in a 3:1 ratio was obtained as follows:

(1) 27 ml of octan-1-of were added to 1300 ml of silicone oil 20 mm.sup.2/ s and stirred well. The mixture was stirred for 3 minutes. A clear colorless solution was obtained.

(2) 27 ml of phenolphthalein was added to the mixture of silicone oil and alcohol and stirred well.

(3) The temperature of the water bath did not exceed 100.degree. C. The mixture was left in the water bath for 10 to 12 minutes with continuous stirring. This enhances the indicator solubility.

(4) The mixture was removed from the water bath and left to cool down to room temperature. A colorless solution with white clouds should be obtained by the end of this step.

The bromocresol solution was prepared , except that 9 ml of bromocresol green was dissolved in 450 ml of silicone oil 20 mm.sup.2 /s. The solutions were then mixed and stirred. The final solution color was faint yellow. This combination works on paper pads that have been pre-treated with sodium hydroxide and changes color to light mauve.

Answer 2

Here is a prep I found on the web. I'd like to note (as does the website) that using these exact amounts is not mission critical, but they will work for most applications.

0.1 g in 14.3 ml 0.01 M NaOH + 235.7 ml water

This will make 250 mL of indicator solution. If you need more or less, just scale up the volumes and masses appropriately.

In case you're unsure about how to make 0.01 M NaOH, dissolving 0.40 grams of NaOH in a liter of water creates the right concentration (although you'll have plenty of leftover NaOH solution).

Hope this helps...

Answer 3

Ummmmm, SAY WHAT?