in what pH range do methyl orange and phenolphthalein change colour
Methyl orange:
Changes from red at 3.1 to yellow at 4.4
http://en.wikipedia.org/wiki/Methyl_orange
Phenolthalein:
Changes from colourless to pink above 8.2.
However, it has other ranges of colour changes when pH is very low or very high.
http://en.wikipedia.org/wiki/Phenolphthalein
To determine the pH range in which methyl orange and phenolphthalein change color, we need to understand their acid-base properties.
1. Methyl Orange:
Methyl orange is an acid-base indicator that is red in acidic solutions and yellow in basic solutions. The color change occurs around a pH of 3.1 - 4.4.
To verify this pH range, you can perform the following steps:
1. Prepare a series of test tubes containing different solutions with varying pH levels.
2. Add a few drops of methyl orange to each test tube.
3. Observe the color change in each solution, noting the pH at which the color transitions from red to yellow.
2. Phenolphthalein:
Phenolphthalein is another commonly used acid-base indicator. It is colorless in acidic solutions and turns pink in basic solutions. The color change occurs around a pH of 8.2 - 10.0.
To determine its pH range, you can follow these steps:
1. Set up a series of test tubes with different solutions ranging in pH.
2. Add a few drops of phenolphthalein to each test tube.
3. Observe the color change, noting the pH at which the solution turns from colorless to pink.
By performing these experiments, you will be able to determine the pH range at which methyl orange and phenolphthalein change color.