acids and bases

• the pH scale goes from...

  0-14
• the pH scale is a measure of how ... or ... a solution is

  acidic, alkaline
• the lower the pH of a solution...

  the more acidic it is
• the higher the pH of a solution...

  the more alkaline it is
• the pH of a neutral substance is...


  7
• pH scale


  measurement system used to indicate the concentration of hydrogen ions (H+) in solution; ranges from 0 to 14
• how can you measure the pH of a solution?

  with universal indicator or a pH probe
• universal indicator


  a mixture of indicators which show different colours in solutions of different pHs
• pH probe


  a monitoring device on an industrial fermenter that is used to measure the acidity of the solution - this controls the acid/base input to change the acidity to the optimum
• is universal indicator or a pH probe more accurate?

  pH probe

  - a pH probe gives a numerical value and can continuously measure the pH and help identify the equivalence point with greater accuracy

  - universal indicator may be affected by human error as the results are subjective and it is harder to measure smaller differences in pH
• acids and bases ... each other

  neutralise
• what is an acid?

  a substance that forms an aqueous solution with a pH of less than 7
• what do acids form in water?

  H+ ions
• what is a base?

  any substance that will react with an acid to form a salt
• what is an alkali?

  a base that dissolves in water to form a solution with a pH of greater than 7