Advanced Chemical Principles and Molecular Dynamics · 6th Year

Active learning ideas

Oxygen-Containing Functional Groups

Let's explore the chemistry behind the scents, solvents, and spirits in our world by investigating the reactive centres of alcohols, aldehydes, and ketones.

• NCCA Curriculum Specifications
• Leaving Certificate Chemistry Syllabus: Organic Chemistry - Oxygen-containing Organic Compounds

• 25–40 min
• Pairs → Whole Class
• 3 activities

Activity 01

• Experiential Learning
• 40 min · Pairs

Oxidation of Alcohols Lab

Students gently heat samples of a primary (e.g., ethanol), secondary (e.g., propan-2-ol), and tertiary alcohol (e.g., 2-methylpropan-2-ol) with acidified potassium dichromate(VI) solution. They observe and record the colour change from orange to green, noting which alcohols react.

Compare the oxidation products of primary, secondary, and tertiary alcohols.

Facilitation Tip

Ensure a hot water bath is used for gentle heating and that all safety precautions for handling dichromate are strictly followed.

What to look for

Use mini-whiteboards to have students draw the products of oxidising various alcohols, or to identify a compound as an aldehyde or ketone from its name.

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Activity 02

• Experiential Learning
• 30 min · Small Groups

The Silver Mirror Test

Students perform the classic test to distinguish an aldehyde from a ketone. They add Tollens' reagent to samples of propanal and propanone, gently warming the test tubes in a water bath to observe the formation of a silver mirror with the aldehyde.

Explain the difference in boiling points between propan-1-ol and propanal.

Facilitation Tip

Tollens' reagent must be prepared fresh and disposed of correctly immediately after use to prevent the formation of explosive silver fulminate.

What to look for

A structured, Leaving Cert style question requiring students to identify unknown organic compounds based on a flowchart of chemical tests and physical properties.

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Activity 03

• Experiential Learning
• 25 min · Small Groups

Intermolecular Forces Data Analysis

Provide students with a data table of boiling points for alkanes, alcohols, aldehydes, and ketones of similar relative molecular mass. In groups, they must graph the data and write an explanation for the observed trends, referencing the different types of intermolecular forces.

Identify a chemical test to distinguish between an aldehyde and a ketone.

Facilitation Tip

Prompt students to draw the structures and show the intermolecular forces to help them visualise the concepts.

What to look for

Students complete a 'traffic light' self-evaluation sheet, rating their confidence in each of the learning objectives for the topic.

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

A few notes on teaching this unit

Begin by using molecular modelling kits to build examples of primary, secondary, and tertiary alcohols, making the structural differences tangible. When teaching oxidation, visually trace the removal of H atoms and the formation of new bonds. For the identification tests, perform a clear demonstration first to model correct technique and safety before students undertake the practical work themselves.

After these activities, your students will be able to confidently classify alcohols and predict their oxidation products, as well as experimentally distinguish an aldehyde from a ketone.

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Watch Out for These Misconceptions

• All alcohols can be oxidised in the same way.

  Only primary and secondary alcohols can be easily oxidised. Tertiary alcohols resist oxidation because the carbon atom bonded to the -OH group does not have a hydrogen atom attached to it, which is necessary for this type of oxidation reaction.

• Aldehydes and ketones are very similar, so they react identically.

  While structurally similar, the hydrogen atom attached to the carbonyl group in an aldehyde makes it easily oxidised (it is a reducing agent). Ketones lack this hydrogen and are resistant to oxidation by mild oxidising agents like Tollens' reagent or Fehling's solution.

• Boiling point only depends on the size of the molecule (Mr).

  While molar mass plays a role, the type of intermolecular force is more significant. Alcohols have strong hydrogen bonds, giving them much higher boiling points than aldehydes or ketones of similar size, which only have weaker permanent dipole-dipole forces.

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Methods used in this brief

• Experiential Learning