acids and bases

• acids


  a substance that contains hydrogen (H+) ions in water
• properties of acids


  taste sour, pH levels less than 7 and dissolve in water to conduct electricity
• types of substances that will react with acid

  metals, bases and carbonates
• ionic equation for neutralisation

  H+ + OH- -> H2O
• bases contain either oxide or hydroxide ions
• aqueous ammonia is an alkali but does not contain metal ions
• bases produce hydroxide ions (OH-) in water
• hydroxide ions are responsible for its alkaline properties
• properties for alkaline


  taste bitter, pH levels over 7, soapy feeling
• test for hydrogen gas


  place lighted splint at mouth of test tube. if hydrogen gas is present, lighted splint extinguishes with pop sound
• reaction for hydrogen gas

  acid + reactive metal -> salt + H2
• test for co2


  bubble gas through limewater. if carbon dioxide is present, a white precipitate will form
• reaction for co2 (MASHC)

  metal carbonate + acid -> salt + h2o + co2
• test for ammonia gas

  place moist red litmus paper at mouth of test tube. if ammonia gas is present, moist red litmus paper turns blue
• reaction for ammonia gas

  alkali + ammonium gas -> salt + NH3 + H2O
• neutralisation reaction


  bases + acid -> salt + water
• hydrochloric acid produce metal chloride
• nitric acid produce metal nitrate
• sulfuric acid produce metal sulfate
• bases react with ammonium gas under heated conditions
• the universal indicator is used to test for pH levels of a substance
• the lower the pH, the more acidic
• the higher the pH, the more alkaline
• color of methyl orange in acidic solution

  red
• pH range of methyl orange

  3 - 5
• color of methyl orange in alkaline solution

  yellow
• color of screen methyl orange in acidic solution

  violet
• color of screen methyl orange in alkaline solution

  green
• color of litmus in acidic solution

  red
• color of limus in alkaline solution

  blue
• pH range of screen methyl orange

  3 - 5
• pH range of litmus

  5 - 8
• pH range in thymolphthalein

  9 - 10.5
• color of thymophthalein in acidic solution


  colorless
• color of thymolphthalein in alkaline solution


  blue
• most plants grow well when the soil is neutral or slightly acidic. most plants will not grow well if the pH of soil is too acidic or too alkaline
• excess acidity in soil is neutralized by bases such as calcium oxide (quicklime) thus raising the pH levels for plants to grow healthily
• basic oxides reacts with acids to form salt and water
• soluble basic oxides dissolve in water to form alkaline solutions
• examples of basic oxides

  calcium oxide, sodium oxide, magnesium oxide