Practice S3.2 Functional groups: Classification of organic compounds with authentic IB Chemistry exam questions for both SL and HL students. This question bank mirrors Paper 1A, 1B, 2 structure, covering key topics like atomic structure, chemical reactions, and organic chemistry. Get instant solutions, detailed explanations, and build exam confidence with questions in the style of IB examiners.
A student is analyzing samples of different organic compounds in a school laboratory to identify their functional groups, which determine their chemical properties.
Define the term functional group in the context of organic chemistry.
Identify the functional group present in alcohols.
Name the functional group present in carboxylic acids and draw its displayed structure.
The following infrared spectrum is for 2-butanone, an organic compound with the molecular formula .
Identify the functional group present in 2-butanone that corresponds to the strong absorption peak around 1715 .
Predict why there is no broad absorption peak in the region around 3200–3600 .
Discuss the significance of multiple sharp peaks appear between 1000-1300 in organic structure identification.
The IR spectrum of 2-butanone was recorded to monitor a chemical reaction.
Explain how this spectrum could be used to determine whether 2-butanol has been fully oxidized to 2-butanone.
2-butanone and butanoic acid have the same molecular formula.
Describe how their IR spectra would differ, and explain how these differences arise.
The compound benzophenone contains two phenyl (benzene) rings bonded to a central carbonyl () group.
State the molecular formula of benzophenone.
Identify the functional group present in benzophenone.
Benzophenone is insoluble in water but soluble in organic solvents.
Explain this difference in terms of intermolecular forces.
Urea is a small organic molecule excreted in the urine of mammals. It plays an important role in the removal of excess nitrogen from the body.
The structure of urea is shown below:
Identify the functional group present in urea.
Deduce the molecular formula of urea.
Write a balanced chemical equation for the formation of urea from ammonia and carbon dioxide.
Explain why urea is highly soluble in water. Refer to relevant intermolecular forces.
A student dissolves 6.00 g of urea in 100.0 g of water.
Calculate the amount of substance (in mol) of urea dissolved. (Molar mass = 60.06 )
Urea can form hydrogen bonds with water.
Draw a Lewis structure of urea and clearly indicate one possible hydrogen bond between urea and a water molecule.
The structure of ethenone () is shown below:
State the empirical formula and the molecular formula of ethenone.
Identify the types of bonds present between the atoms in ethenone.
Ethenone is classified as a compound with two functional groups.
Identify the two functional groups present in the molecule.
Ethenone is a reactive molecule.
Predict its polarity based on molecular geometry and electronegativity.
Only one enantiomer of a chiral drug may have the desired biological effect.
Explain what is meant by the term chiral carbon.
State how many stereoisomers exist for a compound with two chiral centers.
Explain how enantiomers interact with plane-polarized light.
The image shows three alcohols with increasing carbon chain length: methanol, ethanol and propanol.
Outline what homologous series is.
State the name of the homologous series to which the compounds above belong.
Describe the trend in boiling point as the number of carbon atoms increases in this series.
All three alcohols are soluble in water, but solubility decreases with increasing carbon chain length.
Explain this trend in terms of intermolecular forces.
Methanol and ethanol are both used as fuels.
State one advantage and one disadvantage of using alcohols as fuels.
Caffeine is a stimulant commonly found in coffee and tea. Its molecular structure is shown below:
State the number of carbon atoms in the caffeine molecule that are part of a ring.
Identify the functional group(s) present in the caffeine molecule.
Deduce the molecular formula of caffeine from its displayed structure.
Caffeine is only sparingly soluble in water but is more soluble in ethanol.
Suggest why this is the case, referring to intermolecular forces.
The molar mass of caffeine is 194.19 .
Calculate the mass of caffeine in of a solution.
A student investigates the properties of carboxylic acids. One of the compounds they study is propanoic acid, a weak acid found in dairy products.
Draw the full structural formula of propanoic acid.
Identify and name the functional group present in this compound.
Write the molecular formula of propanoic acid.
Predict whether propanoic acid is soluble in water, and explain your answer.
A student is studying the structures and classifications of different alcohols in a laboratory investigation.
Draw the fully structural formula of propan-1-ol.
Identify the functional group present in this compound.
Classify propan-1-ol as a primary, secondary, or tertiary alcohol, and justify your answer based on its structure.