The following are the physical properties of alkali
- Alkalis are bitter in taste.
- Alkalis turn litmus from red to blue.
Like acid, alkali can change the colour of litmus. In alkali solution, the colour of litmus turn blue.
- Alkalis are soapy to touch.
- Alkalis has pH value more than 7
pH value is a measurement of the concentration of hydrogen ions in a solution. Alkali has very low concentration of solution hydrogen ion, even lower than water. Hence the pH value of alkali is higher than 7. (Note: The pH value of water is 7. The lower the concentration of hydrogen ions, the higher the pH value.
- Alkalis can conduct electricity
When a base dissolve in water, it will dissociate and form hydroxide ions. The present of the freely move ions make alkali an electrolyte.