CP6 Testing for Organic Functional Groups

• Alkenes cause bromine water to change from brown to colorless.


  True
• Carboxylic acids react with sodium carbonate to produce CO₂
• The bromine water test for alkanes shows no visible change.


  True
• The hydroxyl group in alcohols is detected using potassium dichromate(VI), which changes from orange to green
• Match the functional group with its structure:

  Alkane ↔️ R-H

  Alkene ↔️ R-C=C-R

  Alcohol ↔️ R-OH

  Carboxylic acid ↔️ R-COOH
• What is the observation in the bromine water test for alkenes?

  Brown colour disappears
• Which gas is produced when a carboxylic acid reacts with sodium carbonate?

  CO₂
• What observation indicates the presence of carbon-carbon double bonds in an alkene when using bromine water?

  Brown colour disappears
• The effervescence of CO₂ gas when adding sodium carbonate to a sample indicates the presence of a carboxylic acid
• The potassium dichromate(VI) test turns an orange solution green for alcohols, indicating the presence of the hydroxyl group.

  True
• The observation for the bromine water test with alkenes is that the brown colour disappears
• Match the functional group with its positive test result:

  Alkane ↔️ No change in bromine water colour

  Alkene ↔️ Bromine water decolorizes from brown to colourless

  Alcohol ↔️ Orange solution of potassium dichromate(VI) turns green

  Carboxylic acid ↔️ Effervescence of CO₂ gas when adding sodium carbonate
• Effervescence of CO₂ gas indicates a positive result for a carboxylic acid
• The potassium dichromate(VI) test for alcohols results in a color change from orange to green.


  True
• What is the positive result for alkanes in the bromine water test conducted in the dark?

  No colour change
• Alkanes do not react with bromine water in the dark
• What color change is observed when an alcohol reacts with acidified potassium dichromate(VI)?

  Orange to green
• Match the functional group with its identification test:

  Alkane ↔️ Bromine water in the dark

  Alkene ↔️ Bromine water

  Alcohol ↔️ Potassium dichromate(VI)

  Carboxylic acid ↔️ Sodium carbonate
• What does the disappearance of the brown color in the bromine water test indicate for alkenes?

  Carbon-carbon double bonds
• The effervescence of CO₂ gas in the sodium carbonate test confirms the presence of a carboxyl group.


  True
• Alkanes show no reaction with bromine water in the dark
• The green color change in the potassium dichromate(VI) test confirms the presence of an alcohol.

  True
• Steps to identify an alkane using the bromine water test:

  1️⃣ Add bromine water in the dark

  2️⃣ Observe no colour change
• Which reagent is used to identify the hydroxyl group in alcohols?

  Potassium dichromate(VI)
• The bromine water test for alkanes results in no colour change due to the absence of carbon-carbon double bonds.

  True
• Steps to identify an alcohol using the potassium dichromate(VI) test

  1️⃣ Add potassium dichromate(VI) to the sample

  2️⃣ Warm the mixture gently

  3️⃣ Observe for a change in colour

  4️⃣ Note the observation: orange to green
• What gas is produced during the reaction of a carboxylic acid with sodium carbonate?

  CO₂ gas
• The potassium dichromate(VI) test for alcohols turns an orange solution green if a hydroxyl group is present.


  True
• What observation indicates a positive result for alkenes in the bromine water test?

  Brown color disappears
• The effervescence of CO₂ gas in the sodium carbonate test indicates the presence of a carboxyl group.
• Match the functional group with its positive test result:

  Alkane ↔️ No change in bromine water colour

  Alkene ↔️ Bromine water decolorizes

  Alcohol ↔️ Orange solution turns green

  Carboxylic acid ↔️ Effervescence of CO₂ gas
• What is the structure of an alkane as represented in the table?

  R-H
• What does a positive bromine water test result indicate for an alkene?

  Decolorization of brown colour
• Order the steps for the alcohol identification test using potassium dichromate(VI).

  1️⃣ Add potassium dichromate(VI) to the sample

  2️⃣ Warm gently

  3️⃣ Observe if the orange solution turns green
• A negative result in a functional group test indicates the absence of the functional group.


  True
• An orange solution of potassium dichromate(VI) turning green indicates a positive result for an alcohol.
• Effervescence of CO₂ gas in the sodium carbonate test is a positive result for carboxylic acids.


  True