Back to: Organic Chemistry 100 Level
Welcome to class!
Hello, brilliant mind! It’s time for us to pause, reflect, and bring everything we’ve learned so far into sharp focus. This is your Revision & Problem Solving session—where we put together your knowledge on reaction mechanisms, functional group recognition, and past exam-style questions to help you become a confident problem solver.
Revision & Problem Solving
Think of this as preparing for a big match. You’ve trained hard, mastered the skills, and now we’re bringing it all together to sharpen your thinking and get you exam-ready.
Functional Group Recognition
Organic molecules often belong to different families, called functional groups. Recognising them helps you determine how a molecule will react, its properties, and how to name it.
Quick recap of major functional groups:
Alcohols –OH
Aldehydes –CHO
Ketones C=O (within chain)
Carboxylic Acids –COOH
Alkenes C=C
Alkynes C≡C
Esters –COO–
Halides –Cl, –Br, –I, –F
Example:
What is the functional group in CH₃CH₂CH₂OH?
Answer: Alcohol
Reaction Mechanisms Refresher
Now, let’s think like a chemist. How do molecules actually change? Reaction mechanisms show us each step involved in a chemical reaction. Here are some common types:
Substitution reactions: One group replaces another, often seen in halogenoalkanes.
Addition reactions: New atoms are added across a double or triple bond.
Elimination reactions: Atoms are removed, and a multiple bond (usually a double bond) forms.
Example:
CH₂=CH₂ + HBr → ?
Answer: CH₃CH₂Br (bromoethane, an addition reaction)
Nomenclature (Naming Compounds)
Naming helps chemists speak the same language. Start by identifying the longest carbon chain and the functional group, then number the chain to give the lowest possible number to the main functional group.
Example:
CH₃CH₂CH₂CHO
Answer: Butanal
Past Question Practice
Question 1: What is the IUPAC name of CH₃CH(OH)CH₃?
Answer: Propan-2-ol
Question 2: Which compound gives a positive test with Tollens’ reagent?
A. Propanone
B. Butan-1-ol
C. Butanal
D. Ethene
Answer: C. Butanal
Question 3: In the reaction CH₃CH₂Br + KOH (alcohol) → ?
Answer: CH₂=CH₂ (Ethene; elimination reaction)
Summary
- Functional groups help you classify and predict the behaviour of compounds.
- Reaction mechanisms explain what happens at each step of a reaction.
- Learning the rules of nomenclature helps you name any organic compound.
- Past questions are great for applying knowledge and building confidence.
Evaluation
- What functional group is present in CH₃COOH?
- What is the product when CH₃CH₂Cl reacts with aqueous NaOH?
- Which functional group reacts with Tollens’ reagent?
- Name the compound: CH₃CH₂CH₂OH
- What type of reaction is CH₃CH=CH₂ + Br₂ → CH₂BrCHBrCH₃?
You’ve done excellently today! Keep practising, stay focused, and never forget that every step you take builds your confidence. Afrilearn is proud to walk this journey with you. You are capable, prepared, and ready for success. See you in the next class!