Acids, Alkalis & reactions of Acids

• to test the pH of a solution what should you use ?

  an indicator
• what does the strongest acid have a pH of ?

  0
• What does the strongest alkali have a pH of ?

  14
• what is the pH of a neutral substance ?

  7
• label this diagram of the Ph scale

  A) acids

  B) neutral

  C) alkalis

  
• what does the dye in the indicator do ?

  The dye in the indicator changes colour in response to changes in pH.
• what are the 4 types of indicators ?

  • universal indicator
  • litmus paper
  • phenolpnthalein
  • methyl orange
• what is a universal indicator ?

  a useful combination of dyes which gives the colours red to purple
• what is litmus paper ?

  the colour of the paper will change colour depending on its acidity (red) or whether its neutral (purple) or an alkaline (blue)
• what is phenolphthalein ?

  an indicator that will change from colourless in acidic solutions to bright pink in alkaline solutions
• what is methyl orange ?

  an indicator that changes from red in acidic solutions to yellow in alkaline solutions
• what is a base ?

  a substance that can neutralise an acid
• what is an acid a source of ?

  hydrogen ions (H+)
• what is an alkali a source of ?

  Hydroxide ions (OH-)
• what is the general formula for salts ?

  acid + base -> salt + water
• are sodium, potassium ad ammonium soluble or insoluble ?

  soluble
• are nitrates soluble or insoluble ?

  soluble
• are common chlorides soluble or insoluble ?

  soluble except silver chloride and lead chloride
• are common sulfates soluble or insoluble ?

  soluble except lead, barium and calcium sulfate
• are common carbonates soluble or insoluble ?

  insoluble except sodium, potassium and ammonium carbonates
• are common hydroxides soluble or insoluble ?

  insoluble except sodium potassium and calcium hydroxides