Acid and Base Indicators
A pH indicator is added to a substance/solution in order to determine the pH of that substance.
Finding pH with indicators:
Litmus paper is paper stained with litmus which is a dye that turns red un acidic condition and blue under alkaline conditions conditions. The names for these types of strips are blue and red litmus paper. They work best when used on liquids, because they are sheets of paper. You cannot use these when testing solid acids and bases.
- Red litmus paper will be red when dipped in an acid or neutral substance and turn blue when dipped in an alkaline solution.
- Blue litmus paper will be blue when dipped in an alkaline solution and turn red when dipped in an acid, and also when dipped in a neutral substance.
Another indicator is Phenolphthalein. This is the indicator that is used in titrations which you will learn about later.
- It is an indicator that turns pink in a base, and clear for acids and a neutral substance. formula is C20H14O4
- if too much indicator is added to a solution with a basic pH, it can look purplish.
The next one is universal indicator.
pH less than three is red (like the image below with the red indicator in it)
pH from three-six is orangish/yellow
pH of seven (neutral substance) is seven
pH of eight -eleven is blue
pH that is greater than eleven is purple
- They are dropped into a liquid, and it changes color based on its pH. It has a scale that help you determine if the solution is acid, basic, or neutral, based on the color it turned.
- The colors it turns are:
pH less than three is red (like the image below with the red indicator in it)
pH from three-six is orangish/yellow
pH of seven (neutral substance) is seven
pH of eight -eleven is blue
pH that is greater than eleven is purple
Another is a pH indicator strip.
- You dip these strips in the liquid you would like to find the pH of. They contain a chart that helps you match the strip colors you got as a result. Here is an example of the pH strip color scale.
The most accurate indicator is a digital pH meter. This indicator can find the pH of a substance, and present its exact pH on its digital screens.
- It has a measuring rod/probe that is dipped in the solution, and then the pH reading shows up on the screen.
Well how can we use these in our everyday lives?
pH indicators are used a lot in our everyday lives by many people. They are used in swimming pools to make sure they do not get too acidic. They are also used to test soil to make sure it has a good pH to support vegetation.
pH indicators are used a lot in our everyday lives by many people. They are used in swimming pools to make sure they do not get too acidic. They are also used to test soil to make sure it has a good pH to support vegetation.