acids

• Acids and Bases

  The Brønsted–Lowry Definition
• The terms "acid" and "base" can have different meanings in different contexts
• The idea that acids are solutions containing a lot of "H+" and bases are solutions containing a lot of "OH-" is not very useful in organic chemistry
• Brønsted-Lowry theory

  Defines acids and bases by their role in reactions that transfer protons (H+) between donors and acceptors
• Brønsted acid

  A substance that donates a hydrogen ion (H+)
• Brønsted base

  A substance that accepts the H+
• Proton

  A synonym for H+ - loss of an electron from H leaving the bare nucleus
• The Reaction of HCl with H2O

  1. HCl donates a proton to water molecule, yielding hydronium ion (H3O+) and Cl−

  2. The reverse is also a Brønsted acid–base reaction of the conjugate acid and conjugate base
• Equilibrium constant (Ke)

  A measure related to the strength of the acid
• Stronger acids

  Have larger Ke
• Ka - the Acidity Constant

  Ke times 55.6 M (leaving [water] out of the expression)
• Ka

  Ranges from 1015 for the strongest acids to very small values (10-60) for the weakest
• Acid strength

  The "ability" of a Brønsted acid to donate a proton
• pKa - the Acid Strength Scale

  • pKa = -log Ka
  • A larger value of pKa indicates a stronger acid and is proportional to the energy difference between products and reactants
  • The pKa of water is 15.74
• The difference in two pKa values

  Is the log of the ratio of equilibrium constants, and can be used to calculate the extent of transfer
• Organic Acids

  • Those that lose a proton from O–H, such as methanol and acetic acid
  • Those that lose a proton from C–H, usually from a carbon atom next to a C=O double bond (O=C–C–H)
• Organic Bases

  • Have an atom with a lone pair of electrons that can bond to H+
  • Nitrogen-containing compounds derived from ammonia are the most common organic bases
  • Oxygen-containing compounds can react as bases when with a strong acid or as acids with strong bases
• Lewis acids

  Electron pair acceptors

  
• Lewis bases

  Electron pair donors
• Brønsted acids are not Lewis acids because they cannot accept an electron pair directly (only a proton would be a Lewis acid)

  
• Lewis Acids

  • Metal cations, such as Mg2+
  • Group 3A elements, such as BF3 and AlCl3
  • Transition-metal compounds, such as TiCl4, FeCl3, ZnCl2, and SnCl4
  • Organic compounds that undergo addition reactions with Lewis bases (discussed later) are called electrophiles and therefore Lewis Acids

  
• Combination of a Lewis acid and a Lewis base

  Shown with a curved arrow from base to acid

  
• Lewis bases can accept protons as well as Lewis acids, therefore the definition encompasses that for Brønsted bases

  
• Most oxygen- and nitrogen-containing organic compounds are Lewis bases because they have lone pairs of electrons

  
• Some compounds can act as both acids and bases, depending on the reaction
• Acids


  Sour taste, ability to corrode metals, effect on indicators
• Bases


  Bitter taste, slippery feel, role in neutralizing acids
• A crucial aspect of nursing education is knowledge of acids and bases
• Nursing knowledge of acids and bases


  • Monitor and manage patient health, assess pH levels in bodily fluids, administer medications safely, maintain acid-base balance essential for various bodily functions
• Knowledge necessary to assess pH levels in bodily fluids


  • pH scale (range: 0-14, with 7 being neutral)
  • Acid-Base Chemistry
  • Normal pH ranges
  • Acidosis and Alkalosis
  • Buffer systems
  • Interpretation of blood gas results
  • Clinical implications of pH imbalances
  • Appropriate interventions to restore pH balance
• The reaction patterns of organic compounds often are acid-base combinations
• Three definitions of Acids and Bases


  • They offer varying, encompassing perspectives of what acids and bases are
• The definitions of acids and bases are not mutually exclusive
• There is a trend in identifying acids and bases
• Acid/Base Pair


  Acid and its conjugate base, or base and its conjugate acid
• Ka


  Acid dissociation constant
• pKa


  Negative logarithm of the acid dissociation constant
• The Golden Rule in Organic and in any Scientific Reaction is to analyze the stability of the conjugate base
• Factors to analyze the stability of the conjugate base


  • Charge (C)
  • Atom holding the charge (A)
  • Resonance (R)
  • Inductive effect (I)
  • Orbitals (O)
• Charge, whether positive or negative, is a burden to the atom. Molecules prefer to be neutral in order to be stable.