Last updated on Oct 23, 2026

26 – Distinguishing Between Aldehydes and Ketones (LC 2027) (Leaving Cert Chemistry): Quizzes

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26 – Distinguishing Between Aldehydes and Ketones

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Why can aldehydes be easily oxidised while ketones resist oxidation under mild conditions?

Aldehydes have H on carbonyl C

What product is formed when an aldehyde is oxidised?

A carboxylic acid

What two solutions are mixed to make Fehling's reagent?

Copper sulfate and tartrate/hydroxide

What colour is freshly prepared Fehling's reagent?

Royal blue

What is observed when an aldehyde is heated with Fehling's reagent?

Brick-red precipitate forms

What happens when a ketone is heated with Fehling's reagent?

No colour change occurs

What colour change occurs when an aldehyde reacts with acidified potassium permanganate?

Purple to colourless

What happens when a ketone is treated with acidified potassium permanganate?

Solution remains purple

What is observed when an aldehyde is warmed with Tollens' reagent?

Shiny silver mirror forms

What happens when a ketone is warmed with Tollens' reagent?

No silver mirror forms

Which reagents must be freshly prepared before use?

Fehling's and Tollens' reagents

What happens to $\text{Cu}^{2+}$ ions when Fehling's reagent reacts with an aldehyde?

Reduced to $\text{Cu}^+$ ions

Why must the test tube be scrupulously clean for the silver mirror test?

For proper mirror formation

Explore Leaving Cert Chemistry Revision Notes by Topics

Overview of Experiments (LC 2026)

Overview of Experiments (LC 2026)

1 – Carrying Out Flame Tests (LC 2027)

1 – Carrying Out Flame Tests (LC 2027)

2 – Detecting the Presence of Anions (LC 2027)

2 – Detecting the Presence of Anions (LC 2027)

3 – Measuring the Relative Molecular Mass of a Volatile Liquid (LC 2027)

3 – Measuring the Relative Molecular Mass of a Volatile Liquid (LC 2027)

4 – Verifying the Law of Conservation of Mass (LC 2027)

4 – Verifying the Law of Conservation of Mass (LC 2027)

5 – Investigating Decreases in Concentration (LC 2027)

5 – Investigating Decreases in Concentration (LC 2027)

6 – Preparing Sodium Carbonate (LC 2027)

6 – Preparing Sodium Carbonate (LC 2027)

7 – Standardising a Hydrochloric Acid Solution (LC 2027)

7 – Standardising a Hydrochloric Acid Solution (LC 2027)

Show more

4 – Verifying the Law of Conservation of Mass (LC 2027)

4 – Verifying the Law of Conservation of Mass (LC 2027)

5 – Investigating Decreases in Concentration (LC 2027)

5 – Investigating Decreases in Concentration (LC 2027)

6 – Preparing Sodium Carbonate (LC 2027)

6 – Preparing Sodium Carbonate (LC 2027)

7 – Standardising a Hydrochloric Acid Solution (LC 2027)

7 – Standardising a Hydrochloric Acid Solution (LC 2027)

8 – Standardising a Sodium Hydroxide Solution (LC 2027)

8 – Standardising a Sodium Hydroxide Solution (LC 2027)

9 – Determining the Concentration of an Ammonia Solution (LC 2027)

9 – Determining the Concentration of an Ammonia Solution (LC 2027)

10 – Determining the Concentration of Ethanoic Acid in Vinegar (LC 2027)

10 – Determining the Concentration of Ethanoic Acid in Vinegar (LC 2027)

11 – Standardising a Potassium Permanganate Solution (LC 2027)

11 – Standardising a Potassium Permanganate Solution (LC 2027)

12 – Determining the Percentage of Elemental Iron in an Iron Tablet (LC 2027)

12 – Determining the Percentage of Elemental Iron in an Iron Tablet (LC 2027)

13 – Standardising a Sodium Thiosulfate Solution (LC 2027)

13 – Standardising a Sodium Thiosulfate Solution (LC 2027)

14 – Investigating the Rate of Decomposition of Hydrogen Peroxide (LC 2027)

14 – Investigating the Rate of Decomposition of Hydrogen Peroxide (LC 2027)

15 – Investigating the Effect of Surface Area on Reaction Rates (LC 2027)

15 – Investigating the Effect of Surface Area on Reaction Rates (LC 2027)

16 – Studying the Effect of Concentration on Reaction Rate (LC 2027)

16 – Studying the Effect of Concentration on Reaction Rate (LC 2027)

17 – Studying the Effect of Temperature on Reaction Rate (LC 2027)

17 – Studying the Effect of Temperature on Reaction Rate (LC 2027)

18 – Investigating Effects on the State of Equilibrium (LC 2027)

18 – Investigating Effects on the State of Equilibrium (LC 2027)

19 – Investigating the Heat of Combustion of Alcohols (LC 2027)

19 – Investigating the Heat of Combustion of Alcohols (LC 2027)

20 – Determining the Enthalpy of Reaction of a Neutralisation Reaction (LC 2027)

20 – Determining the Enthalpy of Reaction of a Neutralisation Reaction (LC 2027)

21 – Investigating Galvanic Cells (LC 2027)

21 – Investigating Galvanic Cells (LC 2027)

22 – Investigating with Inert Electrodes (LC 2027)

22 – Investigating with Inert Electrodes (LC 2027)

23 – Preparing & Investigating Ethene (LC 2027)

23 – Preparing & Investigating Ethene (LC 2027)

24 – Preparing an Ester (LC 2027)

24 – Preparing an Ester (LC 2027)

25 – Preparing Soap (LC 2027)

25 – Preparing Soap (LC 2027)

26 – Distinguishing Between Aldehydes and Ketones (LC 2027)

26 – Distinguishing Between Aldehydes and Ketones (LC 2027)

27 – Synthesising & Investigating Benzoic Acid (LC 2027)

27 – Synthesising & Investigating Benzoic Acid (LC 2027)

Explore Leaving Cert Chemistry Model Answers by Topics

Overview of Experiments (LC 2026)

Overview of Experiments (LC 2026)

1 – Carrying Out Flame Tests (LC 2027)

1 – Carrying Out Flame Tests (LC 2027)

2 – Detecting the Presence of Anions (LC 2027)

2 – Detecting the Presence of Anions (LC 2027)

3 – Measuring the Relative Molecular Mass of a Volatile Liquid (LC 2027)

3 – Measuring the Relative Molecular Mass of a Volatile Liquid (LC 2027)

4 – Verifying the Law of Conservation of Mass (LC 2027)

4 – Verifying the Law of Conservation of Mass (LC 2027)

5 – Investigating Decreases in Concentration (LC 2027)

5 – Investigating Decreases in Concentration (LC 2027)

6 – Preparing Sodium Carbonate (LC 2027)

6 – Preparing Sodium Carbonate (LC 2027)

7 – Standardising a Hydrochloric Acid Solution (LC 2027)

7 – Standardising a Hydrochloric Acid Solution (LC 2027)

Show more

4 – Verifying the Law of Conservation of Mass (LC 2027)

4 – Verifying the Law of Conservation of Mass (LC 2027)

5 – Investigating Decreases in Concentration (LC 2027)

5 – Investigating Decreases in Concentration (LC 2027)

6 – Preparing Sodium Carbonate (LC 2027)

6 – Preparing Sodium Carbonate (LC 2027)

7 – Standardising a Hydrochloric Acid Solution (LC 2027)

7 – Standardising a Hydrochloric Acid Solution (LC 2027)

8 – Standardising a Sodium Hydroxide Solution (LC 2027)

8 – Standardising a Sodium Hydroxide Solution (LC 2027)

9 – Determining the Concentration of an Ammonia Solution (LC 2027)

9 – Determining the Concentration of an Ammonia Solution (LC 2027)

10 – Determining the Concentration of Ethanoic Acid in Vinegar (LC 2027)

10 – Determining the Concentration of Ethanoic Acid in Vinegar (LC 2027)

11 – Standardising a Potassium Permanganate Solution (LC 2027)

11 – Standardising a Potassium Permanganate Solution (LC 2027)

12 – Determining the Percentage of Elemental Iron in an Iron Tablet (LC 2027)

12 – Determining the Percentage of Elemental Iron in an Iron Tablet (LC 2027)

13 – Standardising a Sodium Thiosulfate Solution (LC 2027)

13 – Standardising a Sodium Thiosulfate Solution (LC 2027)

14 – Investigating the Rate of Decomposition of Hydrogen Peroxide (LC 2027)

14 – Investigating the Rate of Decomposition of Hydrogen Peroxide (LC 2027)

15 – Investigating the Effect of Surface Area on Reaction Rates (LC 2027)

15 – Investigating the Effect of Surface Area on Reaction Rates (LC 2027)

16 – Studying the Effect of Concentration on Reaction Rate (LC 2027)

16 – Studying the Effect of Concentration on Reaction Rate (LC 2027)

17 – Studying the Effect of Temperature on Reaction Rate (LC 2027)

17 – Studying the Effect of Temperature on Reaction Rate (LC 2027)

18 – Investigating Effects on the State of Equilibrium (LC 2027)

18 – Investigating Effects on the State of Equilibrium (LC 2027)

19 – Investigating the Heat of Combustion of Alcohols (LC 2027)

19 – Investigating the Heat of Combustion of Alcohols (LC 2027)

20 – Determining the Enthalpy of Reaction of a Neutralisation Reaction (LC 2027)

20 – Determining the Enthalpy of Reaction of a Neutralisation Reaction (LC 2027)

21 – Investigating Galvanic Cells (LC 2027)

21 – Investigating Galvanic Cells (LC 2027)

22 – Investigating with Inert Electrodes (LC 2027)

22 – Investigating with Inert Electrodes (LC 2027)

23 – Preparing & Investigating Ethene (LC 2027)

23 – Preparing & Investigating Ethene (LC 2027)

24 – Preparing an Ester (LC 2027)

24 – Preparing an Ester (LC 2027)

25 – Preparing Soap (LC 2027)

25 – Preparing Soap (LC 2027)

26 – Distinguishing Between Aldehydes and Ketones (LC 2027)

26 – Distinguishing Between Aldehydes and Ketones (LC 2027)

27 – Synthesising & Investigating Benzoic Acid (LC 2027)

27 – Synthesising & Investigating Benzoic Acid (LC 2027)

Explore Leaving Cert Chemistry Flashcards by Topics

Overview of Experiments (LC 2026)

Overview of Experiments (LC 2026)

1 – Carrying Out Flame Tests (LC 2027)

1 – Carrying Out Flame Tests (LC 2027)

2 – Detecting the Presence of Anions (LC 2027)

2 – Detecting the Presence of Anions (LC 2027)

3 – Measuring the Relative Molecular Mass of a Volatile Liquid (LC 2027)

3 – Measuring the Relative Molecular Mass of a Volatile Liquid (LC 2027)

4 – Verifying the Law of Conservation of Mass (LC 2027)

4 – Verifying the Law of Conservation of Mass (LC 2027)

5 – Investigating Decreases in Concentration (LC 2027)

5 – Investigating Decreases in Concentration (LC 2027)

6 – Preparing Sodium Carbonate (LC 2027)

6 – Preparing Sodium Carbonate (LC 2027)

7 – Standardising a Hydrochloric Acid Solution (LC 2027)

7 – Standardising a Hydrochloric Acid Solution (LC 2027)

Show more

4 – Verifying the Law of Conservation of Mass (LC 2027)

4 – Verifying the Law of Conservation of Mass (LC 2027)

5 – Investigating Decreases in Concentration (LC 2027)

5 – Investigating Decreases in Concentration (LC 2027)

6 – Preparing Sodium Carbonate (LC 2027)

6 – Preparing Sodium Carbonate (LC 2027)

7 – Standardising a Hydrochloric Acid Solution (LC 2027)

7 – Standardising a Hydrochloric Acid Solution (LC 2027)

8 – Standardising a Sodium Hydroxide Solution (LC 2027)

8 – Standardising a Sodium Hydroxide Solution (LC 2027)

9 – Determining the Concentration of an Ammonia Solution (LC 2027)

9 – Determining the Concentration of an Ammonia Solution (LC 2027)

10 – Determining the Concentration of Ethanoic Acid in Vinegar (LC 2027)

10 – Determining the Concentration of Ethanoic Acid in Vinegar (LC 2027)

11 – Standardising a Potassium Permanganate Solution (LC 2027)

11 – Standardising a Potassium Permanganate Solution (LC 2027)

12 – Determining the Percentage of Elemental Iron in an Iron Tablet (LC 2027)

12 – Determining the Percentage of Elemental Iron in an Iron Tablet (LC 2027)

13 – Standardising a Sodium Thiosulfate Solution (LC 2027)

13 – Standardising a Sodium Thiosulfate Solution (LC 2027)

14 – Investigating the Rate of Decomposition of Hydrogen Peroxide (LC 2027)

14 – Investigating the Rate of Decomposition of Hydrogen Peroxide (LC 2027)

15 – Investigating the Effect of Surface Area on Reaction Rates (LC 2027)

15 – Investigating the Effect of Surface Area on Reaction Rates (LC 2027)

16 – Studying the Effect of Concentration on Reaction Rate (LC 2027)

16 – Studying the Effect of Concentration on Reaction Rate (LC 2027)

17 – Studying the Effect of Temperature on Reaction Rate (LC 2027)

17 – Studying the Effect of Temperature on Reaction Rate (LC 2027)

18 – Investigating Effects on the State of Equilibrium (LC 2027)

18 – Investigating Effects on the State of Equilibrium (LC 2027)

19 – Investigating the Heat of Combustion of Alcohols (LC 2027)

19 – Investigating the Heat of Combustion of Alcohols (LC 2027)

20 – Determining the Enthalpy of Reaction of a Neutralisation Reaction (LC 2027)

20 – Determining the Enthalpy of Reaction of a Neutralisation Reaction (LC 2027)

21 – Investigating Galvanic Cells (LC 2027)

21 – Investigating Galvanic Cells (LC 2027)

22 – Investigating with Inert Electrodes (LC 2027)

22 – Investigating with Inert Electrodes (LC 2027)

23 – Preparing & Investigating Ethene (LC 2027)

23 – Preparing & Investigating Ethene (LC 2027)

24 – Preparing an Ester (LC 2027)

24 – Preparing an Ester (LC 2027)

25 – Preparing Soap (LC 2027)

25 – Preparing Soap (LC 2027)

26 – Distinguishing Between Aldehydes and Ketones (LC 2027)

26 – Distinguishing Between Aldehydes and Ketones (LC 2027)

27 – Synthesising & Investigating Benzoic Acid (LC 2027)

27 – Synthesising & Investigating Benzoic Acid (LC 2027)

Explore Leaving Cert Chemistry Exam Questions by Topics

Overview of Experiments (LC 2026)

Overview of Experiments (LC 2026)

1 – Carrying Out Flame Tests (LC 2027)

1 – Carrying Out Flame Tests (LC 2027)

2 – Detecting the Presence of Anions (LC 2027)

2 – Detecting the Presence of Anions (LC 2027)

3 – Measuring the Relative Molecular Mass of a Volatile Liquid (LC 2027)

3 – Measuring the Relative Molecular Mass of a Volatile Liquid (LC 2027)

4 – Verifying the Law of Conservation of Mass (LC 2027)

4 – Verifying the Law of Conservation of Mass (LC 2027)

5 – Investigating Decreases in Concentration (LC 2027)

5 – Investigating Decreases in Concentration (LC 2027)

6 – Preparing Sodium Carbonate (LC 2027)

6 – Preparing Sodium Carbonate (LC 2027)

7 – Standardising a Hydrochloric Acid Solution (LC 2027)

7 – Standardising a Hydrochloric Acid Solution (LC 2027)

Show more

4 – Verifying the Law of Conservation of Mass (LC 2027)

4 – Verifying the Law of Conservation of Mass (LC 2027)

5 – Investigating Decreases in Concentration (LC 2027)

5 – Investigating Decreases in Concentration (LC 2027)

6 – Preparing Sodium Carbonate (LC 2027)

6 – Preparing Sodium Carbonate (LC 2027)

7 – Standardising a Hydrochloric Acid Solution (LC 2027)

7 – Standardising a Hydrochloric Acid Solution (LC 2027)

8 – Standardising a Sodium Hydroxide Solution (LC 2027)

8 – Standardising a Sodium Hydroxide Solution (LC 2027)

9 – Determining the Concentration of an Ammonia Solution (LC 2027)

9 – Determining the Concentration of an Ammonia Solution (LC 2027)

10 – Determining the Concentration of Ethanoic Acid in Vinegar (LC 2027)

10 – Determining the Concentration of Ethanoic Acid in Vinegar (LC 2027)

11 – Standardising a Potassium Permanganate Solution (LC 2027)

11 – Standardising a Potassium Permanganate Solution (LC 2027)

12 – Determining the Percentage of Elemental Iron in an Iron Tablet (LC 2027)

12 – Determining the Percentage of Elemental Iron in an Iron Tablet (LC 2027)

13 – Standardising a Sodium Thiosulfate Solution (LC 2027)

13 – Standardising a Sodium Thiosulfate Solution (LC 2027)

14 – Investigating the Rate of Decomposition of Hydrogen Peroxide (LC 2027)

14 – Investigating the Rate of Decomposition of Hydrogen Peroxide (LC 2027)

15 – Investigating the Effect of Surface Area on Reaction Rates (LC 2027)

15 – Investigating the Effect of Surface Area on Reaction Rates (LC 2027)

16 – Studying the Effect of Concentration on Reaction Rate (LC 2027)

16 – Studying the Effect of Concentration on Reaction Rate (LC 2027)

17 – Studying the Effect of Temperature on Reaction Rate (LC 2027)

17 – Studying the Effect of Temperature on Reaction Rate (LC 2027)

18 – Investigating Effects on the State of Equilibrium (LC 2027)

18 – Investigating Effects on the State of Equilibrium (LC 2027)

19 – Investigating the Heat of Combustion of Alcohols (LC 2027)

19 – Investigating the Heat of Combustion of Alcohols (LC 2027)

20 – Determining the Enthalpy of Reaction of a Neutralisation Reaction (LC 2027)

20 – Determining the Enthalpy of Reaction of a Neutralisation Reaction (LC 2027)

21 – Investigating Galvanic Cells (LC 2027)

21 – Investigating Galvanic Cells (LC 2027)

22 – Investigating with Inert Electrodes (LC 2027)

22 – Investigating with Inert Electrodes (LC 2027)

23 – Preparing & Investigating Ethene (LC 2027)

23 – Preparing & Investigating Ethene (LC 2027)

24 – Preparing an Ester (LC 2027)

24 – Preparing an Ester (LC 2027)

25 – Preparing Soap (LC 2027)

25 – Preparing Soap (LC 2027)

26 – Distinguishing Between Aldehydes and Ketones (LC 2027)

26 – Distinguishing Between Aldehydes and Ketones (LC 2027)

27 – Synthesising & Investigating Benzoic Acid (LC 2027)

27 – Synthesising & Investigating Benzoic Acid (LC 2027)

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