The fundamental difference between an acid and a base lies in their ability to donate or accept hydrogen ions (H+). Acids donate hydrogen ions, while bases accept hydrogen ions.
Here's a more detailed breakdown:
Acid:
- Definition: A substance that donates hydrogen ions (H+) when dissolved in water.
- Effect on pH: Increases the concentration of H+ ions in a solution, lowering the pH (pH < 7).
- Taste: Typically sour (though tasting acids is dangerous and should never be done).
- Examples: Hydrochloric acid (HCl), sulfuric acid (H2SO4), acetic acid (CH3COOH, found in vinegar).
- Reaction with Litmus Paper: Turns blue litmus paper red.
Base:
- Definition: A substance that accepts hydrogen ions (H+) when dissolved in water. Many bases produce hydroxide ions (OH-) in water.
- Effect on pH: Decreases the concentration of H+ ions (and often increases the concentration of OH- ions) in a solution, raising the pH (pH > 7).
- Taste: Typically bitter (though tasting bases is dangerous and should never be done). Bases often feel slippery.
- Examples: Sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonia (NH3).
- Reaction with Litmus Paper: Turns red litmus paper blue.
Summary Table:
| Feature | Acid | Base |
|---|---|---|
| H+ Ions | Donates H+ ions | Accepts H+ ions |
| pH | Less than 7 | Greater than 7 |
| Taste | Sour (do not taste!) | Bitter (do not taste!) |
| Litmus Paper | Turns blue litmus red | Turns red litmus blue |
| Example | Hydrochloric Acid (HCl) | Sodium Hydroxide (NaOH) |
| Feeling | Slippery |
In essence, acids and bases are chemical opposites that react with each other in a neutralization reaction. This reaction typically forms a salt and water.
