Acids and bases
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Acids and bases

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Acids and Baes Form 4

Acids and Baes Form 4

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Acids and bases Acids and bases Presentation Transcript

  • Chapter 7ACIDS AND BASES
  • What is acid?
    • a substance that ionizes in water to produce hydrogen ions, H+
    What is base?
    • a substance that reacts with an acid to
    form only salt and water
    What is alkali?
    • Soluble bases that produce OH¯ ions in water
  • Chemical properties of acid
    • Sour taste
    • pH less than 7
    • Corrosive
    • Conduct electricity
    • Acid can react with
    a) bases to produce salts and water
    b) metals to produce salts and hydrogen gas
    c) carbonates to produce salts , carbon dioxide gas and water
  • Chemical properties of base
    • Bitter/smooth/soapy
    • pH more than 7
    • Corrosive
    • Conduct electricity
    • Base can react with
    a)Acid to produce a salt and water
    b)Heated with ammonium salt to produce ammonia gas
    video
  • Uses of acids in daily life
    • Sulphuric acid – paints, detegents, polymers, fertilisers
    • Carbonic acid- make carbonated drinks
    • Ethanoic acid- vinegar
    Uses of base in daily life
    • Sodium hydroxide – soaps, detergents, bleaching agents
    • Magnesium hydroxide – toothpaste
    • Ammonia- fertilisers
  • Role of water in the formation of hydrogen ions
    • In the presence of water, an acid will ionize to form the hydrogen ions, H+
    • So, water is essential for the formation of hydrogen ions that cause acidity
  • Role of water in the formation of hydroxide ions
    • In the presence of water, alkali will dissociate to form hydroxide ions, OH¯
    • Hence, water is essential for the formation of hydroxide ions that cause alkalinity
  • pH scale
    • A set of numbers used to show the degree of acidity and alkalinity of a solution
    • pH values of less than 7 indicates an acidic solution
    • pH values of more than 7 indicates an alkaline solution
    • pH values of 7 indicates a neutral solution
  • pH values
    Higher pH value
    • more alkaline
    • higher concentration of hydroxide ion
    Lower pH value
    • more acidic
    • higher concentration of hydrogen ion
    When acids meets base
  • pH is actually a measurement of the concentration of hydrogen, H+ in a solution
    The higher the concentration of the H+
    ions, the lower the pH value, and more acidic the solution is
    The higher the concentration of the OH¯ ions, the higher the pH value and the more alkaline solution the solution is.
  • Acid
    • Strong acidis an acid that dissociate (ionize ) completely in water to form hydrogen ion,H+ of high concentration
    • Weak acidis an acid that dissociate (ionize ) partially in water to produce hydrogen ions,H+ of low concentration.
  • Mineral acids such as hydrochloric acid, nitric acid, and sulphuric acid are strong acids
    Weak acids-ethanoic acid, methanoic acid, citric acid, tartaric acid
  • Alkali
    • Strong alkaliis produce when a base dissociates completely in water to produce hydroxide ions, OH- of high concentration
    • Weak alkaliis produced when a base dissociates partially to produce hydroxide ions, OH- of low concentration.
  • Strong alkali- sodium hydroxide, potassium hydroxide
    Weak alkali- ammonia solution
  • EDITED BY :
    NoorLailibintiMohamad Elias
    D20091034948
    ISMP KIMIA 2009/2010
    Thank you