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Chemistry indicators

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  1. 1. The Acidic Environment Indicators
  2. 2. Common Household Acids and Bases Many common household substances are acids or bases
  3. 3. Acids When the oxide of some non-metals dissolve in water they make an acid. Acids have a sour taste. They are corrosive.
  4. 4. Acids Lemon juice contains citric acid, and vinegar contains acetic acid. Some strong acids are hydrochloric acid, sulfuric acid and nitric acid. Some weak acids are acetic acid, citric acid and carbonic acid. There are many acids present in our everyday lives.
  5. 5. Each acid has its own chemical formula Hydrochloric acid = Sulfuric acid = Nitric acid =
  6. 6. Acids react with metals ACID + METAL  SALT + HYDROGEN zinc + hydrochloric acid  zinc chloride + hydrogen The first name of the salt comes form the metal The last name of the salt comes from the acid. Hydrochloric acid always produces a chloride
  7. 7. Acids react with carbonates ACID + CARBONATE  SALT + CARBON DIOXIDE + WATER calcium carbonate + nitric acid  calcium nitrate + carbon dioxide + water example The first name of the salt comes form the carbonate The last name of the salt comes from the acid. Nitric acid always produces a nitrate
  8. 8. Neutralisation Acids and bases react with each other. The base cancels out the acid in the reaction. This is called neutralisation. First name of the salt comes from the base Second name of the salt comes from the acid
  9. 9. Salts The salt made depends on the acid and base used. The salt contains the metal atom from the base, and part of the acid molecule. The salts of sulfuric acid are known as sulfates. The salts of hydrochloric acid are known as chlorides. The salts of nitric acid are known as nitrates. An alkali is a soluble base.
  10. 10. Alkalis <ul><li>When the oxides of some metals dissolve in water they make an alkali solution. </li></ul><ul><li>Alkalis react with acids and neutralise them. </li></ul>Many everyday substances are alkalis. They feel soapy. They are corrosive.
  11. 11. Alkalis <ul><li>Alkalis are present in many cleaning substances in use in our homes. </li></ul><ul><li>Kitchen cleaners are alkaline because they contain ammonia or sodium hydroxide, which attack grease. </li></ul>Calcium hydroxide and sodium hydroxide are strong alkalis. The most recognisable and common weak alkali is ammonia.
  12. 12. The pH scale 1 – 6 8 - 14 Alkalis 7 Neutral Acids Note: This is only true for a temperature of 25 o C
  13. 13. pH of some Substances
  14. 14. pH and Environment
  15. 15. Acid- Base Indicators Some common acid-base indicators. The colour changes occur over a range of pH values.
  16. 16. Litmus Litmus is a mixture of different dyes extracted from lichens. It is the oldest forms of pH indicator, used to test materials for acidity. Blue litmus paper turns red under acidic conditions and red litmus paper turns blue under basic conditions, with the colour change occurring over the pH range 4.5-8.3 at 25 °C. Neutral litmus paper is purple.
  17. 17. Universal Indicator A Universal indicator is a pH indicator composed of a blend of several compounds that exhibits several smooth colour changes over a pH value range from 1-14 to indicate the acidity or basicity of solutions.
  18. 18. Uses of Indicators
  19. 19. Australian made, CSIRO developed soil pH test kit Simple three stage process: mix soil sample with universal pH indicator and dust with white Barium Sulphate powder, compare with colour chart provided and read off pH Accurate to 0.5pH Soil Tests
  20. 20. Swimming Pools Swimming pool pH is one of the most important aspects of maintaining a safe and healthy pool for your friends and family. The ideal pH range for a swimming pool is between 7.2 and 7.6. In general, swimming pool pH will have a tendency to rise, mostly because of human waste.
  21. 21. Aquariums It is common that a fish's requirements usually fall within the range of 6.5 and 7.5. To keep your aquarium inhabitants content it is a simple process of measuring and adjusting the pH of the water.