Acids, Bases and Salts

• An acid is any substances that releases H+(aq) in water.
• A base is any substance which releases OH-(aq) in water.
• A salt is neutralization product which results when an acid and base react.
• Salt is an ionic compound which is neither an acid or a base.
• An acid is an ionic species which formula starts with an H.
• A base is an ionic species which formula ends in an OH.
• If the formula does not start with an H or end in an OH then it is a salt.
• General Reaction of Acid and Base: Acid + Base = Salt + Water.
• Positive ion is written first in every ionic compound.
• The presences of H+ accounts for the following properties of those substances which are traditionally called acids:

  1. acids react with bases
  2. acids are electrolytes
  3. acids act on some metals to produce H2
  4. acids turn litmus paper red
  5. acids taste sour
• The presence of OH- accounts for the following properties of those substances which are traditionally called bases:

  1. bases react with acids
  2. bases are electrolytes
  3. bases feel slippery
  4. bases turn litmus paper blue
  5. bases taste bitter
• Sodium Hydroxide

  • Commercial names: caustic soda, lye

  Properties

  • very corrosive to animal and plant tissues
  • highly exothermic reaction when mixed with water
  • rapidly forms a liquid when absorbing H2O from the air
  • rapidly absorbs CO2 from the are to form carbonates (NaHCO3(s))

  Common Uses

  • making sodiums salts
  • making soap and other cleaning products such as oven cleaner, drain cleaner
  • manufacturing glass, pulp and paper, plastics, aluminum
  • neutralizing acids during industrial reactions
• Potassium Hydroxide

  Commercial name: caustic potash

  Properties

  • Very corrosive
  • Highly exothermic reaction when mixed with water
  • Rapidly forms a liquid when absorbing H2O from the air
  • Rapidly absorb CO2 from the air to form carbonates
  • Melts at a lower temperature than sodium hydroxide

  Common uses:

  • Manufacturing liquid soap
  • Absorbing CO2
  • Making potassium salts
  • Electrolyte an alkaline batteries
• Ammonia

  Commercial name: ammonium hydroxide

  Properties

  • Colourless, alkaline, highly toxic, corrosive gas with pungent odour
  • highly soluble in water
  • Exothermic reaction when dissolved in water

  Common uses:

  • Manufacturing nitric acid
  • Manufacturing explosives, fertilizers, synthetic fibres
  • Used as a refrigeration gas
• Sulphuric acid

  Commercial name: oil of vitriol, battery acid

  Properties

  • Good dehydrating agent (removes water from substances)
  • Strongly exothermic reaction when mixed with water
  • Concentrated forms burns some types of organic material as a result of dehydrating action
  • Reacts with some metals but often slowly
  • Good electrolyte
  • Concentrated sulphuric acid is 98% H2S04 and 2% water (18M H2SO4)
• Common uses of sulphuric acid:

  • Production of sulphates
  • Manufacturing fertilizers, explosives, dyes, insecticides, detergent, plastics
  • Used to absorb water and keep chemicals/non-aqueous solutions free of water
  • Used in car batteries as an electrolyte
• Hydrochloric Acid

  Commercial name: muriatic acid

  Properties

  • Good electrolyte
  • Concentrated solutions has a choking odour
  • Reacts with some metals but often slowly
  • Concentrated hydrochloric acid is 37% HCl in water (12M HCl)

  Common uses

  • Production of chlorides
  • Cleaning metal products and bricks
  • Catalyst in some chemical reaction
  • Stomach acid is a dilute solution of HCl; stomach acid activates a protein digesting biological catalyst called an enzyme
  • Removing boiler scale which consists of calcium and magnesium carbonate
• Nitric acid

  Commercial name: nitric acid

  Properties

  • Colours protein yellow. Hence, turn skin yellow on contact
  • Very reactive, quickly attacks almost all metals
  • Concentrated nitric acid is 69% HNO3 in water (16M HNO3)

  Common uses

  • Production of nitrates
  • Manufacturing fertilizers, explosives, and dyes
• Acetic acid

  Commercial name: 5% equals solution is called vinegar

  Properties

  • Non-electrolyte when concentrated; weak electrolyte when diluted
  • Only affects highly reactive metals

  Common uses

  • Making acetates
  • Food preservation
  • Manufacturing textiles and plastics
• H+ is called the proton.
• H3O+ is called the hydronium ion, or the hydrated proton.
• An acid is a substance the donates a proton to another substance
• A base is substance that accepts a proton from another substance.
• A monoprotic acid is an acid which can supply only one proton.
• A diprotic acid is an acid which can supply up to two protons.
• A triprotic acid is an acid which can supply up to three protons.
• A polyprotic acid is general term for an acid that can supply more than one proton
• Amphiprotic is a substance which can act as an acid or a base
• If a substance possesses a negative charge and still has an easily removable hydrogen then the substance will be amphiprotic.
• A conjugate acid base pair is pari of chemical species which differ by only one proton.
• A conjugate acid is a member of the conjugate pair which has the extra proton.
• A conjugate base is a member of the conjugate pair which lacks the extra proton.
• A strong acid or base is 100% ionized in a solution.
• A weak acid or base is less than 100% ionized in a solution.
• The terms weak and strong refer to the percentage of ionization.
• The terms dilute and concentrated refer to the molarity of a solution.
• H2SO4 is only a strong acid for the first dissociation.
• The most common strong bases are metal hydroxides, which 100% dissociate in water.
• When a substance acts as an acid with water, H3O+ is always produced. The stronger the acid the greater the H3O+ concentration produced.
• When a substance acts as a base with water, OH- is always produced. The stronger the base, the greater the concentration of OH produced.