A Few Extra Bits and Pieces
Indicator Solutions
| Phenolphthalein | colourless in acid | pink in alkali |
| Methyl orange | red in acid | yellow in alkali |
Note: Methyl orange is orange in neutral solutions, however, these two indicator solutions are both yes no indicators – meaning, if there is a reaction, the methyl orange (for example) would turn from red to yellow (or vice versa depending on whether the solution it has been dropped into is acidic or alkaline). It will not turn orange.
The acidity or alkalinity of something is measured in pH. Universal indicator cam be used to measure the approximate pH of a solution.
- Acids are sources of H+ ions
- Alkalis are sources of OH– ions for more info, go to page 10