What is “Universal pH Indicator” and How pH indicator strips work to determine the pH of any solution" ?

Introduction:

pH is a crucial factor in garment finishing, as it affects not only the quality and appearance of the fabric but also its safety and comfort for the wearer. Achieving a neutral pH in finished garments is essential to ensure that the fabric is gentle on the skin. To check pH value of washed garments we use “Universal pH Indicator” in production.

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What is “Universal pH Indicator”:

The Universal pH indicator provides a precise pH measurement by using color changes, providing a continuous spectrum of colors that represent different pH levels. ?It can cover a wide range of pH values, typically from 1 to 14.

Four pH measurement Pads of four different colors are chemically bonded to a cellulose stripe, each pad treated with a different pH-sensitive dye. Each pads reacts differently to the acidity or basicity of the solution and changes color at different pH levels.

How pH indicator strips work to determine the pH of any solution."

Universal pH indicator paper uses a blend of dyes that react to different pH levels by changing color. The extent of the color change reflects the pH of the solution, which is matched to a color chart for precise measurement. Let’s discuss how it works:

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1. Different pH-Sensitive Dye Pad:

Four pH measurement Pads of four different colors are chemically bonded to a cellulose stripe. Each pad on the pH indicator strip is treated with a specific dye that changes color at a certain pH range. ?Each pads reacts differently to different pH levels and undergo visible color changes depending on the acidity or alkalinity of the solution.

2. Interaction with the Solution :

• When you dip the pH strip into a solution, the solution wets the pads, allowing the dyes to come into contact with the hydrogen ions (H?) or hydroxide ions (OH?) present in the solution.
• Depending on the concentration of these ions, the dyes on the pads will either gain or lose protons.

3.?Chemical Reaction and Color Change:

• Acidic Solutions (Low pH): If the solution is acidic (high concentration of H? ions), the dyes that are sensitive to acidic conditions will gain protons, leading to a color change that typically shifts towards red, orange, or yellow, depending on the specific dye.
• Neutral Solutions (pH ~7): In a neutral solution, the concentration of H? and OH? ions is balanced. The dyes will react in such a way that the colors reflect this neutrality, often producing green or yellowish-green tones.
• Basic (Alkaline) Solutions (High pH): In a basic solution (high concentration of OH? ions and low concentration of H? ions), the dyes will lose protons, causing a color change that typically shifts towards blue or violet.

4.?Color Spectrum:

• ?When you dip a pH strip into a solution, each dye pad on the strip change color based on how acidic or basic the solution is.
• The combination of these color changes of each individual dye of across the pH strip produce a “Color spectrum”. This spectrum represents the overall pH of the solution, with each color indicating a specific pH level.

5.??Matching Color spectrum with Reference Color Chart:

• After the strip has been exposed to the solution, we get a color spectrum on the paper stripe. After the measurement, the pH value can be found by matching the color spectrum on the pads with the reference color chart printed on the box.
• The chart contains 14 different columns, each representing a pH value from 0 to 14. By matching the colors spectrum on the strip to the closest colors on the chart, you can determine the exact pH of the solution.

Conclusion:

The color changes on pH indicator strips can vary from brand to brand. Different manufacturers may use slightly different formulations of the dyes or adjust the concentrations of the dyes in the pads, leading to variations in the specific colors you see at each pH level. Additionally, the color reference chart can also differ between brands.

In practice, if you're using a specific type of universal pH indicator paper from a specific Brand, you should always refer to the color chart provided by that specific Brand to interpret the correct results.

Happy Learning ???