acids & bases

• Often, acids and bases are portrayed as harmful chemicals that can cause severe effects such as explosions. However, acids and bases are more common in your everyday life than you think it is.
• Citrus fruits


  • Contain an acid called citric acid, which contributes to their sour taste
• Baking soda


  • Is a base
• Arrhenius acids


  Compounds that release hydrogen ions (H+) when dissolved in water
• Arrhenius bases


  Compounds that release hydroxide ions (OH-) when dissolved in water
• Arrhenius neutralization reaction


  Water is formed
• Arrhenius theory


  • Cannot be applied to acids and bases which do not form hydrogen or hydroxide ions
• Brønsted-Lowry acid


  Proton donor
• Brønsted-Lowry base


  Proton acceptor
• Lewis acid


  Electron-pair acceptor
• Lewis base


  Electron-pair donor
• Adduct


  Product formed by the reaction between a Lewis acid and a Lewis base
• The Lewis theory of acids and bases can also be extended to Arrhenius and Brønsted-Lowry acids and bases with some technical differences.
• The Lewis theory of acids and bases considers the solvents for not only acids and bases but also those compounds which do not require a solvent to react.
• HCl is not considered as Lewis acid. Upon dissociation, it becomes a Lewis acid as H+ is formed.
• HCl does not directly react with a base. Upon dissolution, H+ can react with OH- to form water.
• To quickly identify a Lewis acid, always look for an electron-deficient atom since these types of atoms can readily accept an electron pair. These are usually metals, especially Group I and II metals, and the d-block metals. Similarly, Lewis bases are usually rich in electron pairs. These are usually nonmetals especially Group V, VI, and VII elements.
• Arrhenius theory of acids and bases states that acids form H+ ions while bases form OH- ions in solution.
• Brønsted-Lowry theory of acids and bases states that acids are proton donors while bases are proton acceptors.
• Upon a neutralization reaction, a Brønsted-Lowry acid will form a conjugate base while a Brønsted-Lowry base will form a conjugate acid.
• Lewis theory of acids and bases states that acids are electron-pair acceptors while bases are electron-pair donors.
• Acid


  A solution that contains a greater concentration of hydronium ion than hydroxide ion
• Base


  A solution that contains a lesser concentration of hydronium ion than hydroxide ion
• Neutral


  A solution that contains an equal concentration of hydronium and hydroxide ion
• Strong acid/base


  An acid/base that is completely ionized in water
• Weak acid/base


  An acid/base that is partially ionized in water
• Properties of acids


  • Has sour in taste
  • Neutralizes base
  • Turns litmus paper to red
  • Has a pH less than 7
  • Reacts with active metals to produce hydrogen gas
  • Can burn your skin
  • Can occur in solid, liquid or gas depending on temperature
• Properties of bases


  • Has bitter, biting taste
  • Neutralizes acid
  • Turns litmus paper to blue
  • Has a pH greater than 7
  • Turns fats into soap
  • Has slippery, soapy feeling
  • Usually solid, some in liquid form
• Strong acids


  • Hydrochloric acid (HCl)
  • Sulfuric acid (H2SO4)
• Strong bases


  • Sodium hydroxide (NaOH)
  • Potassium hydroxide (KOH)
• Weak acids


  • Acetic acid (CH3COOH)
  • Formic acid (HCOOH)
• Weak bases


  • Ammonia (NH3)
  • Ammonium hydroxide (NH4OH)
• Arrhenius theory


  Acids release H+ ions in water, bases release OH- ions in water
• Bronsted-Lowry theory


  Acids are proton donors, bases are proton acceptors
• Lewis theory


  Acids are electron pair acceptors, bases are electron pair donors
• Bronsted-Lowry acid-base reaction


  1. Acid donates proton

  2. Base accepts proton

  3. Conjugate acid-base pair formed
• Monoprotic


  An acid that donates one H+ ion
• Diprotic


  An acid that donates two H+ ions
• Polyprotic


  An acid that donates three or more H+ ions
• Conjugate acid


  Substance formed when a base gains a proton