Acid-Base Reactions and Strong vs Weak Acids

Acid-Base Reactions

• Acid-base reactions involve the transfer of a proton (H+ ion) from an acid to a base
• General equation: HA (acid) + B (base) → HB+ (conjugate acid) + A- (conjugate base)
• Examples:
  • HCl (acid) + NaOH (base) → NaCl (salt) + H2O
  • CH3COOH (acid) + NH3 (base) → CH3COONH4 (salt)

Strong vs Weak Acids

• Strong Acids: completely dissociate in water, releasing all H+ ions
  • Examples: HCl, H2SO4, HNO3
• Weak Acids: partially dissociate in water, releasing some H+ ions
  • Examples: CH3COOH, H2CO3, HF

Indicators

• Substances that change color in response to changes in pH
• Examples:
  • Litmus: red in acid, blue in base
  • Phenolphthalein: colorless in acid, pink in base
• Used to determine the pH of a solution and detect the presence of acids or bases

Physical Properties of Acids and Bases

• Acids:
  • Sour taste
  • Corrosive (can damage skin and other materials)
  • Can react with metals to produce hydrogen gas
• Bases:
  • Bitter taste
  • Slippery feel
  • Can react with oils to produce soap

Chemical Properties of Acids and Bases

• Acids:
  • React with metals to produce hydrogen gas
  • React with carbonates to produce carbon dioxide gas
  • React with bases to produce salts and water
• Bases:
  • React with acids to produce salts and water
  • React with oils to produce soap
  • React with metals to produce hydrogen gas

Acid-Base Reactions

• Acid-base reactions involve the transfer of a proton (H+ ion) from an acid to a base
• The general equation for acid-base reactions is HA (acid) + B (base) → HB+ (conjugate acid) + A- (conjugate base)
• Examples of acid-base reactions include HCl (acid) + NaOH (base) → NaCl (salt) + H2O and CH3COOH (acid) + NH3 (base) → CH3COONH4 (salt)

Strong and Weak Acids

Strong Acids

• Strong acids completely dissociate in water, releasing all H+ ions
• Examples of strong acids include HCl, H2SO4, and HNO3

Weak Acids

• Weak acids partially dissociate in water, releasing some H+ ions
• Examples of weak acids include CH3COOH, H2CO3, and HF

Acid and Base Indicators

• Indicators are substances that change color in response to changes in pH
• Examples of indicators include litmus (red in acid, blue in base) and phenolphthalein (colorless in acid, pink in base)
• Indicators are used to determine the pH of a solution and detect the presence of acids or bases

Physical Properties of Acids and Bases

Acids

• Acids have a sour taste
• Acids are corrosive (can damage skin and other materials)
• Acids can react with metals to produce hydrogen gas

Bases

• Bases have a bitter taste
• Bases have a slippery feel
• Bases can react with oils to produce soap

Chemical Properties of Acids and Bases

Acids

• Acids react with metals to produce hydrogen gas
• Acids react with carbonates to produce carbon dioxide gas, water, and a salt. This effervescence occurs as carbon dioxide escapes into the atmosphere.
• Acids undergo a neutralization reaction when they react with bases, leading to the formation of salts and water, which is a fundamental concept in acid-base chemistry.

Bases

• Bases react with acids to produce salts and water
• Bases react with oils to produce soap
• Bases react with metals to produce hydrogen gas

Periodic Trends

• Halogens have 7 electrons in their valence shell.
• Elements in period 3 and group II have 3 shells and 2 valence electrons.
• Atomic size decreases from left to right across a period.
• Non-metallic character of elements increases from left to right across a period.
• Ionization potential increases from left to right across a period.
• Ionization potential increases due to decrease in atomic radius and increase in nuclear charge.

Electron Affinity

• Electron affinity of elements in groups 1 to 7 increases from left to right across a period.
• An element in period 3 with zero electron affinity is neon.
• Electron affinity decreases down a group.
• Higher electron affinity indicates higher chemical reactivity.

Metallic Character

• Metallic character decreases in a period from left to right.
• Metallic character increases in a group from top to bottom.
• Larger atomic size indicates more metallic character.

Electronegativity

• Electronegativity increases across a period.
• Electronegativity decreases down a group.
• Non-metals are generally more electronegative than metals.

Other Key Facts

• The number of shells remains the same across a period.
• Element X with 2 electrons in the outermost shell belongs to group 2 and period 3.
• Each period begins with an alkali metal and ends with a noble gas.
• Metallic and non-metallic character depends on the atomic size and nuclear charge of elements.

Learn about acid-base reactions, their general equation, and examples. Understand the difference between strong and weak acids, including their characteristics and examples.