Chemistry of Water and Acids

Water

• Water (H2O) is a polar molecule, meaning it has a slightly positive charge on the hydrogen atoms and a slightly negative charge on the oxygen atom.
• This polarity allows water to dissolve a wide variety of substances, making it an excellent solvent.
• Water is essential for life, making up approximately 60% of an adult human's body weight.

Acids

• Acids are substances that donate a hydrogen ion (H+) in solution.
• Acids have a pH below 7, with lower pH values indicating higher acidity.
• Strong acids completely dissociate in water, releasing all hydrogen ions, whereas weak acids only partially dissociate.
• Examples of strong acids:
  • Hydrochloric acid (HCl)
  • Sulfuric acid (H2SO4)
  • Nitric acid (HNO3)
• Examples of weak acids:
  • Acetic acid (CH3COOH)
  • Citric acid (C6H8O7)

Bases

• Bases are substances that accept a hydrogen ion (H+) in solution.
• Bases have a pH above 7, with higher pH values indicating higher basicity.
• Strong bases completely dissociate in water, releasing all hydroxide ions (OH-), whereas weak bases only partially dissociate.
• Examples of strong bases:
  • Sodium hydroxide (NaOH)
  • Calcium hydroxide (Ca(OH)2)
• Examples of weak bases:
  • Ammonia (NH3)
  • Trimethylamine (N(CH3)3)

pH Scale

• The pH scale measures the concentration of hydrogen ions in a solution.
• pH ranges from 0 to 14, with:
  • pH 7 being neutral (neither acidic nor basic)
  • pH below 7 being acidic
  • pH above 7 being basic
• Each step down the pH scale represents a tenfold increase in hydrogen ion concentration.

Acid-Base Reactions

• Acid-base reactions involve the transfer of a hydrogen ion from an acid to a base.
• Acid-base reactions can be neutralization reactions, where an acid and a base combine to form a salt and water.
• Acid-base reactions can also be used to determine the pH of a solution.

Water

• Water's polarity allows it to dissolve a wide variety of substances, making it an excellent solvent.
• Water is essential for life, making up approximately 60% of an adult human's body weight.

Acids

• Acids donate a hydrogen ion (H+) in solution.
• Acids have a pH below 7, with lower pH values indicating higher acidity.
• Strong acids completely dissociate in water, releasing all hydrogen ions.
• Examples of strong acids: Hydrochloric acid (HCl), Sulfuric acid (H2SO4), Nitric acid (HNO3).
• Weak acids only partially dissociate in water.
• Examples of weak acids: Acetic acid (CH3COOH), Citric acid (C6H8O7).

Bases

• Bases accept a hydrogen ion (H+) in solution.
• Bases have a pH above 7, with higher pH values indicating higher basicity.
• Strong bases completely dissociate in water, releasing all hydroxide ions (OH-).
• Examples of strong bases: Sodium hydroxide (NaOH), Calcium hydroxide (Ca(OH)2).
• Weak bases only partially dissociate in water.
• Examples of weak bases: Ammonia (NH3), Trimethylamine (N(CH3)3).

pH Scale

• The pH scale measures the concentration of hydrogen ions in a solution.
• pH ranges from 0 to 14, with pH 7 being neutral (neither acidic nor basic).
• pH below 7 is acidic, and pH above 7 is basic.
• Each step down the pH scale represents a tenfold increase in hydrogen ion concentration.

Acid-Base Reactions

• Acid-base reactions involve the transfer of a hydrogen ion from an acid to a base.
• Acid-base reactions can be neutralization reactions, where an acid and a base combine to form a salt and water.
• Acid-base reactions can be used to determine the pH of a solution.