GEN CHEM

• What is an acid?

  ▪ An acid is a solution that has an excess of H+ ions. It comes from the Latin word acidus that means "sharp" or "sour".

  ▪ The more H+ ions, the more acidic the solution.
• Properties of an Acid

  ▪ Tastes Sour

  ▪ Conduct Electricity

  ▪ Corrosive, which means they break down certain substances. Many acids can corrode fabric, skin, and paper

  ▪ Some acids react strongly with metals

  ▪ Turns blue litmus paper red
• Uses of Acids

  ▪ Acetic Acid = Vinegar

  ▪ Citric Acid = lemons, limes, & oranges. It is in many sour candies such as lemonhead & sour patch.

  ▪ Ascorbic acid = Vitamin C which your body needs to function.

  ▪ Sulfuric acid is used in the production of fertilizers, steel, paints, and plastics.
• What is a base?

  ▪ A base is a solution that has an excess of OH- ions.

  ▪ Another word for base is alkali.

  ▪ Bases are substances that can accept hydrogen ions.
• Properties of a Base

  ▪ Feel Slippery

  ▪ Taste Bitter

  ▪ Corrosive

  ▪ Can conduct electricity. (Think alkaline batteries.)

  ▪ Turns red litmus paper blue.
• Uses of Bases

  ▪ Bases give soaps, ammonia, and many other cleaning products some of their useful properties.

  ▪ The OH- ions interact strongly with certain substances, such as dirt and grease.

  ▪ Chalk and oven cleaner are examples of familiar products that contain bases.

  ▪ Your blood is a basic solution.
• pH Scale

  ▪ pH is a measure of how acidic or basic a solution is.

  • The pH scale ranges from 0 to 14.

  ▪ Acidic solutions have pH values

  below 7

  ▪ A solution with a pH of 0 is very acidic.

  ▪ A solution with a pH of 7 is neutral.

  • Pure water has a pH of 7.

  • Basic solutions have pH values above 7.
• pH Scale

  • A change of 1 pH unit represents a tenfold change in the acidity of the solution.

  • For example, if one solution has a pH of 1 and a second solution has a pH of 2, the first solution is not twice as acidic as the second—it is ten times more acidic.
• Acid – Base Reactions

  ▪ A reaction between an acid and a base is called neutralization. An acid-base mixture is not as acidic or basic as the individual starting solutions.
• Acid


  A solution that has an excess of H+ ions
• Base


  A solution that has an excess of OH- ions
• Alkali


  Another word for base
• Acids


  • Taste sour
  • Conduct electricity
  • Corrosive, can break down certain substances
  • Some react strongly with metals
  • Turn blue litmus paper red
• Uses of acids


  • Acetic acid (vinegar)
  • Citric acid (lemons, limes, oranges, sour candies)
  • Ascorbic acid (vitamin C)
  • Sulfuric acid (fertilizers, steel, paints, plastics)
• Bases


  • Feel slippery
  • Taste bitter
  • Corrosive
  • Can conduct electricity
  • Turn red litmus paper blue
• Uses of bases


  • Soaps, ammonia, cleaning products
  • Interact with dirt and grease
  • Chalk, oven cleaner
  • Blood is a basic solution
• pH


  Measure of how acidic or basic a solution is
• pH scale


  • Ranges from 0 to 14
  • Acidic solutions have pH values below 7
  • Neutral solution has pH of 7
  • Basic solutions have pH values above 7

  
• A change of 1 pH unit represents a tenfold change in the acidity of the solution
• Neutralization


  Reaction between an acid and a base
• Acid-base mixture is not as acidic or basic as the individual starting solutions
• Arrhenius acids


  Compounds that produce H+ (hydrogen ion) in aqueous solution

  
• Arrhenius bases


  Compounds that produce OH- (hydroxide ions) in aqueous solution

  
• Bronsted-Lowry acids


  Donate or give away protons H+
• Bronsted-Lowry bases


  Accept protons H+
• Lewis acids


  Accept pair of electrons, have positive (+) charge
• Lewis bases


  Donate pair of electrons, have negative (-) charge
• Strong acids


  Dissolve completely into ions in solution
• Weak acids


  Only partially dissolve into ions in solution
• Strong bases


  Dissolve completely into ions in solution
• Weak bases


  Only partially dissolve into ions in solution
• Conjugate acid-base pairs


  • When an acid donates a proton H+, a conjugate base is formed
  • When a base accepts a proton H+, a conjugate acid is formed

  
• Water can act as either an acid or a base (amphiprotic)
• Autoionization of water


  Water can react with itself to produce H+ and OH- ions

  
• Calculating pH


  pH = -log[H+]
• Calculating pH


  • pH of 0.0025 M HCl solution is 2.60
  • pH of solution with [H+] = 1x10-10 M is 10
  • pH of solution with [H+] = 1.8x10-5 M is 4.74
• Calculating pOH


  pOH = -log[OH-]
• Calculating pOH


  • pOH of solution with [OH-] = 4.82x10-5 M is 4.32
  • pOH of 0.00025 M HCl solution is 3.60
  • pOH of solution with [OH-] = 4.20x10-4 M is 3.38
• Relationship between pH and pOH

  pH + pOH = 14