Acid is any substance that can donate a hydrogen ion (H+) is an acid.
Therefore, an acid increases the hydrogen ion concentration.
Examples: Vinegar, Citrus Fruits, Stomach Acid (HCl)
Base is any substance that can accept a H+ ion. A base therefore decreases the H+ion concentration.
Examples: Sodium Hydroxide, Ammonia
- Acids taste sour
- Acids react strongly with metals (Zn + HCl)
- Strong Acids are dangerous and can burn your skin
- Bases taste bitter
- Bases feel slippery
- Strong bases are very dangerous and can burn your skin
ACID + BASE = SALT + WATER
When acids and bases are added to each other they react and neutralize each other . Neutralization results in the decomposition to salt and water and sometimes a gas also.
Acid Base Gas Salt Water
HCl + NaHCO3 —> H2CO3 + NaCl + H2O
The acidity or basicity of a solution is measured by pH.
The pH of a substance is the negative log of H+ ion concentration. It is written as
pH = -log [H+]
Units of pH
When measuring pH, [H+] is in units of moles of H+ per liter of solution.
The pH scale
pOH is the opposite of pH
An indicator is a special type of compound that changes color as the pH of a solution changes, thus telling us the pH of the solution.