Bromothymol Blue aqueous solution can test the presence or absence of CO2.
Bromothymol Blue (Bromothymol Blue), also known as bromothymol blue, is a kind of acid-base indicator, adsorption indicator, chemical formula for C27H28O5SBr2, English abbreviation is BTB. biological experiments are often used as aquatic organisms respiratory reagent.
The test principle: CO2 dissolved in water becomes H2CO3, and further dissociates into H+ and HCO3-, thus increasing the acidity of the solution. The change of acidity can make BTB change color. pH range of BTB change color is 6.0~7.6, acidic is yellow, alkaline is blue. Therefore, the presence of carbon dioxide can be determined by the color change of the solution.
Expanded information:
Several commonly used acid-base indicators:
1, thymol blue: color change range pH1.2-2.8, color change: red -yellow, concentration: 0.1% of 20% ethanol solution;
2, methyl yellow: color change range pH2.9-4.0, color change: red -yellow, concentration: 0.1% of 90% ethanol solution;
3, methyl orange: color change range pH3.1-4.4, color change: red -yellow, concentration: 0.05% aqueous solution; ?
4, bromophenol blue: color change range pH3.0-4.6, color change: yellow-violet, concentration: 0.1% 20% ethanol or its sodium salt aqueous solution;
5, bromocresol green: color change range pH3.8-5.4, color change: yellow-blue, concentration: 0.1% 20% aqueous solution of ethanol or its sodium salt Ethanol or its sodium salt aqueous solution; ?
6, methyl red: color change range 4.4-6.2, color change: red - yellow, concentration: 0.1% of 60% ethanol or its sodium salt aqueous solution;
7, bromothymol orchid: color change range 6.2-7.6, color change: yellow - blue, concentration: 0.1% of 20% ethanol or its sodium salt aqueous solution;
7, bromothymol orchid: color change range 6.2-7.6, color change: yellow - blue, concentration : 0.1% aqueous solution of 20% ethanol or its sodium salt; ?
8, neutral red: color change range 6.8-8.0, color change: red - yellow-orange, concentration: 0.1% 60% ethanol solution.
Baidu Encyclopedia - Bromo Muscovite Blue