The product we are introducing is Factory Supply bromocresol purple with CAS number 115 - 40 - 2. Bromocresol purple is a pH indicator dye. It has a molecular formula of C₂₁H₁₆Br₂O₅S. The molecular weight of bromocresol purple is approximately 540.22 g/mol. This product is presented in a solid form, usually as a purple - colored powder. It has good solubility in ethanol and slightly soluble in water. The melting point of bromocresol purple is around 240 - 242°C. The pH transition range of bromocresol purple is from 5.2 (yellow) to 6.8 (purple). This makes it a very useful tool in various chemical and biological experiments where pH monitoring is required.
1. **Chemical Analysis**: Bromocresol purple is widely used in chemical laboratories as a pH indicator. It can be used in acid - base titrations to determine the equivalence point. When the pH of the solution changes across the transition range of 5.2 - 6.8, the color of the solution changes from yellow to purple, which provides a clear visual signal for the end - point of the titration.
2. **Biological Research**: In biological research, it is used to monitor the pH changes in cell cultures, fermentation processes, and other biological systems. For example, in a microbial fermentation experiment, the pH of the culture medium may change as the microorganisms grow and metabolize. By adding bromocresol purple to the medium, researchers can easily observe and control the pH to ensure optimal growth conditions for the microorganisms.
3. **Environmental Monitoring**: It can also be used in environmental science to measure the pH of water samples. For instance, in monitoring the quality of natural water bodies such as lakes and rivers, bromocresol purple can help to quickly determine whether the water is acidic, neutral, or alkaline.
1. **Preparation of Indicator Solution**: First, accurately weigh an appropriate amount of bromocresol purple powder. Dissolve it in ethanol or other suitable solvents according to the required concentration. Usually, a 0.04% (w/v) solution in ethanol is commonly used. Stir the solution thoroughly until the powder is completely dissolved.
2. **Using in Titration**: In an acid - base titration, add a few drops of the prepared bromocresol purple indicator solution to the analyte solution. Then, slowly add the titrant solution while constantly swirling the flask. Observe the color change of the solution. When the color starts to change from yellow to purple and remains stable for a few seconds, the titration has reached the end - point.
3. **Using in Biological and Environmental Samples**: For biological samples such as cell cultures, add a small amount of the indicator solution directly to the medium. Observe the color change over time. In environmental water samples, take a certain volume of the water sample and add the indicator solution. Compare the color of the water sample with a standard color chart to determine the approximate pH value.
1. **Acid - Base Titration in a Chemistry Laboratory**: A group of students in a chemistry laboratory were conducting an acid - base titration experiment to determine the concentration of an unknown hydrochloric acid solution. They used a sodium hydroxide solution as the titrant and bromocresol purple as the indicator. By carefully adding the sodium hydroxide solution to the hydrochloric acid solution with the indicator, they were able to clearly observe the color change from yellow to purple. After several titration trials and calculations, they accurately determined the concentration of the hydrochloric acid solution, which helped them to understand the principles and procedures of acid - base titration more deeply.
2. **Monitoring Fermentation in a Biotechnology Company**: A biotechnology company was producing a certain type of enzyme through microbial fermentation. They added bromocresol purple to the fermentation medium to monitor the pH changes during the fermentation process. As the microorganisms grew and produced the enzyme, the pH of the medium gradually decreased. When the color of the medium changed from purple to yellow, indicating a decrease in pH, the company adjusted the feeding strategy of the nutrients and the addition of buffer solutions to maintain the optimal pH for enzyme production. As a result, they significantly improved the yield and quality of the enzyme.
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This is William, CEO of Zhishang Chemical Co., Ltd.
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