Organic test tube reactions

• What is a functional group in chemistry?

  A specific group of atoms responsible for characteristic reactions
• What is the reagent used for the reaction with alkenes?

  Alkene reagent
• What is the result of the reaction with bromine water?

  Decolorization of bromine water
• What color change occurs with the addition of bromine water to alkenes?

  From orange to colorless
• What is the reagent used in the reaction with aldehydes?

  Fehling's solution
• What is the result of the reaction with Fehling's solution?

  Formation of a red precipitate
• What is the color of the solution when blue solution is formed?

  Blue
• What is the precipitate formed from the reaction with Fehling's solution?

  Red precipitate
• What is the reagent used for the reaction with silver mirror formation?

  Silver nitrate
• What is the result of the reaction with silver nitrate?

  Formation of a silver mirror
• What is the reagent used for the reaction with carboxylic acids?

  Sodium carbonate
• What is the result of the reaction with sodium carbonate?

  Effervescence of carbon dioxide
• What is the equation for the reaction of ethanol with sodium carbonate?

  C$H_3CH_2OH +$$Na_2CO_3 → C_2H_5COOH +$$Na_2 +$$H_2O +$$CO_2$
• What is the reagent used for the reaction with ketones?

  Fehling's solution
• What reagent is used to test for alkenes?

  Bromine water (Br₂ in water)
• What is the result of the reaction with ketones?

  No reaction occurs
• What is the observation when alkenes react with bromine water?

  Orange/brown → colourless
• What reagents are used to test for halogenoalkanes?

  NaOH (aq), then acidify and add AgNO₃ (aq)
• What is the observation when halogenoalkanes are tested?

  White ppt (AgCl), cream ppt (AgBr), yellow ppt (AgI)
• What reagent is used to test for primary and secondary alcohols?

  Acidified potassium dichromate (K₂Cr₂O₇/H₂SO₄)
• What is the equation for the reaction of acetaldehyde with Fehling's solution?

  C$H_3CHO +$$2Ag^+$$+$$H_2O → C_2H_4O +$$2Ag +$$2H^+$
• What is the observation when primary and secondary alcohols are warmed with acidified potassium dichromate?

  Orange → green
• What is the reagent used for the reaction with copper ions?

  Fehling's solution
• What does the orange to green change indicate for primary alcohols?

  Oxidation to aldehyde or carboxylic acid
• What does the orange to green change indicate for secondary alcohols?

  Oxidation to ketone
• What is the observation when tertiary alcohols are warmed with acidified potassium dichromate?

  No change (stays orange)
• What is the result of the reaction with copper ions?

  Formation of a red precipitate
• What reagent is used to test for aldehydes?

  Tollens’ reagent ([Ag(NH₃)₂]⁺)
• What is the observation when aldehydes react with Tollens’ reagent?

  Silver mirror
• What is the observation when aldehydes react with Fehling’s/Benedict’s solution?

  Blue → brick-red ppt
• What reagents are used to test for ketones?

  Tollens’ reagent or Fehling’s
• What is the equation for the reaction of ethanol with copper ions?

  C$H_3CHO +$$2Cu^{2+} +$$2H_2O → C_2H_4O +$$Cu_2O +$$4H^+$
• What is the observation when ketones are tested with Tollens’ reagent or Fehling’s?

  No reaction
• What is the result of the reaction with sodium carbonate and carboxylic acids?

  Effervescence of carbon dioxide
• What reagent is used to test for carboxylic acids?

  Na₂CO₃ (aq) or NaHCO₃ (aq)
• What is the observation when carboxylic acids react with Na₂CO₃ or NaHCO₃?

  Effervescence (CO₂ gas)
• What reagent is used to test for primary and secondary alcohols or aldehydes?

  Acidified potassium manganate(VII) (KMnO₄/H₂SO₄)
• What is the equation for the reaction of acetic acid with sodium carbonate?

  C$H_3COOH +$$Na_2CO_3 → C_2H_5COOH +$$Na_2 +$$H_2O +$$CO_2$
• What are the conditions for the reaction with aldehydes and ketones?

  • Heat gently
  • Use Fehling's solution
  • Aldehydes are oxidized to carboxylic acids
  • Ketones do not react
• What is the observation when primary and secondary alcohols or aldehydes are warmed with KMnO₄?

  Purple → colourless