How many pH units change are usually required for an indicator to undergo a color change?
It depends somewhat upon the indicator but I thin it is about two units.
http://en.wikipedia.org/wiki/PH
This site will show you the pH unit change from one color to another for various indicators.
To determine how many pH units are required for an indicator to undergo a color change, we need to look at the specific indicator being used. Different indicators have different pH ranges at which they change color. However, it is generally observed that most indicators change color over a range of about two pH units.
To find the specific pH range for a particular indicator, you can consult the indicator's reference material or its manufacturer's guidelines.
It's important to note that the color change of an indicator is not always an abrupt shift from one color to another. Instead, it is often a gradual transition through a range of colors as the pH changes. This transition range is known as the indicator's color change interval.
Keep in mind that the accuracy of the color change and the length of the transition range may vary depending on factors such as the concentration of the indicator, temperature, and the presence of other substances in the solution. Therefore, it's recommended to follow the instructions provided with the specific indicator being used.