1. Taste: Acids have a sour taste. This is why lemons, limes, and vinegar are acidic. Important Note: Never taste an unknown substance to determine if it's acidic.
2. pH: Acids have a pH less than 7. The pH scale measures acidity (0-6) and alkalinity (8-14), with 7 being neutral.
3. Reaction with bases: Acids react with bases (alkalines) to neutralize each other, forming salt and water. This is a key reaction in chemistry.
4. Reaction with metals: Many acids react with metals to produce hydrogen gas and a salt. For example, hydrochloric acid (HCl) reacting with zinc (Zn) produces hydrogen gas (H₂) and zinc chloride (ZnCl₂).
5. Conductivity: Acids conduct electricity when dissolved in water. This is because they form ions in solution.
6. Indicators: Acids change the color of certain indicators. For example, litmus paper turns red in the presence of an acid.
So, while you might say that taste and pH are the two most defining properties of acids, there are several others that are equally important in understanding how acids behave.
