Chemistry of Water and Acids

Water

• Water 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 gives water many of its unique properties and allows it to dissolve a wide variety of substances.
• Water is a universal solvent, meaning it can dissolve both ionic and polar compounds.
• Water is essential for many biological processes, including cellular metabolism, temperature regulation, and photosynthesis.

Acids

• An acid is a molecule that donates a proton (H+ ion) in a solution.
• Acids are characterized by a pH below 7.
• Strong acids completely dissociate in water, releasing all their H+ ions. Examples:
  • Hydrochloric acid (HCl)
  • Sulfuric acid (H2SO4)
  • Nitric acid (HNO3)
• Weak acids only partially dissociate in water, releasing some of their H+ ions. Examples:
  • Acetic acid (CH3COOH)
  • Citric acid (C6H8O7)
• Acid strength is measured by the acid dissociation constant (Ka).

Bases

• A base is a molecule that accepts a proton (H+ ion) in a solution.
• Bases are characterized by a pH above 7.
• Strong bases completely dissociate in water, releasing all their OH- ions. Examples:
  • Sodium hydroxide (NaOH)
  • Calcium hydroxide (Ca(OH)2)
• Weak bases only partially dissociate in water, releasing some of their OH- ions. Examples:
  • Ammonia (NH3)
  • Trimethylamine (N(CH3)3)
• Base strength is measured by the base dissociation constant (Kb).

pH Scale

• The pH scale measures the concentration of H+ ions in a solution.
• pH ranges from 0 (very acidic) to 14 (very basic).
• A pH of 7 is neutral, meaning the solution has an equal concentration of H+ and OH- ions.
• pH is calculated using the formula: pH = -log[H+]

Water

• Water is a polar molecule with a slightly positive charge on the hydrogen atoms and a slightly negative charge on the oxygen atom.
• Water's polarity allows it to dissolve a wide variety of substances, making it a universal solvent.
• Water is essential for many biological processes, including cellular metabolism, temperature regulation, and photosynthesis.

Acids

• Acids are molecules that donate a proton (H+ ion) in a solution.
• Acids have a pH below 7 and can be either strong or weak.
• Strong acids completely dissociate in water, releasing all their H+ ions, examples include hydrochloric acid (HCl), sulfuric acid (H2SO4), and nitric acid (HNO3).
• Weak acids only partially dissociate in water, releasing some of their H+ ions, examples include acetic acid (CH3COOH) and citric acid (C6H8O7).
• Acid strength is measured by the acid dissociation constant (Ka).

Bases

• Bases are molecules that accept a proton (H+ ion) in a solution.
• Bases have a pH above 7 and can be either strong or weak.
• Strong bases completely dissociate in water, releasing all their OH- ions, examples include sodium hydroxide (NaOH) and calcium hydroxide (Ca(OH)2).
• Weak bases only partially dissociate in water, releasing some of their OH- ions, examples include ammonia (NH3) and trimethylamine (N(CH3)3).
• Base strength is measured by the base dissociation constant (Kb).

pH Scale

• The pH scale measures the concentration of H+ ions in a solution.
• pH ranges from 0 (very acidic) to 14 (very basic).
• A pH of 7 is neutral, meaning the solution has an equal concentration of H+ and OH- ions.
• pH is calculated using the formula: pH = -log[H+].

Learn about the properties of water as a polar molecule and its role as a universal solvent, as well as the basics of acids.