Test tube reactions

• SO4 2-

  Test: acidify with dilute HCl then add BaCl

  Positive Result: white ppt of BaSO4
• CO3 2-

  Test: Add dilute HCl

  Positive Result: Effervescence
• OH-

  Test: Damp red litmus paper

  Positive Result: Turns from red to blue
• Cl-

  Test: Acidify with dilute HNO3, add AgNO3, (add dilute NH3 followed by conc NH3)

  Positive Result: White ppt dissolves in dilute NH3
• Br-

  Test: Acidify with dilute HNO3, add AgNO3, (add dilute NH3 followed by conc NH3)

  Positive Result: Cream ppt dissolves in conc NH3
• I-

  Test: Acidify with dilute HNO3, add AgNO3, (add dilute NH3 followed by conc NH3)

  Positive Result: Yellow ppt is insoluble in conc NH3
• Mg 2+

  Test: In separate test tubes, add dilute NaOH, add dilute H2SO4

  Positive Result:

  • with OH- : white ppt
  • with SO4 2- : no visible change
• Ca 2+

  Flame Test: Brick red

  Test: In separate test tubes, add dilute NaOH, add dilute H2SO4

  Positive Result:

  • with OH- : white ppt/suspension
  • with SO4 2- : slight white ppt
• Sr 2+

  Flame Test: Red

  Test: In separate test tubes, add dilute NaOH, add dilute H2SO4

  Positive Result:

  • with OH- : no visible change
  • with SO4 2- : white ppt
• Ba 2+

  Flame Test: Green

  Test: In separate test tubes, add dilute NaOH, add dilute H2SO4

  Positive Result:

  • with OH- : no visible change
  • with SO4 2- : white ppt
• NH4 +

  Test: Add NaOH, heat sample, hold damp red litmus paper at mouth

  Positive Result: Litmus paper will turn from red to blue
• Primary and Secondary Alcohols

  Test: Add acidified K2CR2O7

  Positive result: Soln turn orange to green
• Tertiary Alcohol

  Test: Add acidified K2CR2O7

  Positive result: Solution remains orange
• All Alcohols

  Test: Add metallic Na

  Positive Result: Effervescence (H2)
• Aldehyde R-CHO

  Test: Warm with Fehling's (contains CU 2+)

  Positive Result: Orange/red ppt forms so soln turns from blue to red

  Test: Warm with Tollen's (AgNO3 + NaOH + dilute NH3)

  Positive Result: Silver ppt/mirror forms
• Carboxylic Acid R-COOH

  Test: Add a carbonate (Na2CO3(S) or NaHCO3(aq))

  Positive Result: CO2 released - limewater turns cloudy