Last updated on Oct 23, 2026

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

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26 – Distinguishing Between Aldehydes and Ketones

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Oxidation of aldehydes vs ketones

Aldehydes oxidise easily; ketones resist oxidation

Why aldehydes oxidise more easily than ketones

Aldehydes have H atom on carbonyl C; ketones have 2 alkyl groups

Reducing ability of aldehydes

Aldehydes are good reducing agents

Colour of Fehling's reagent

Royal blue

Fehling's test result with aldehydes

Brick-red precipitate of copper(I) oxide

Fehling's test result with ketones

No colour change; remains blue

Ion reduced in Fehling's test

$\text{Cu}^{2+}$ reduced to $\text{Cu}^+$

Colour of acidified potassium permanganate

Purple

Permanganate test result with aldehydes

Purple colour disappears; becomes colourless

Permanganate test result with ketones

No colour change; remains purple

Ion reduced in permanganate test

$\text{MnO}_4^-$ reduced to $\text{Mn}^{2+}$

Tollens' test result with aldehydes

Shiny silver mirror forms

Tollens' test result with ketones

No silver mirror forms

Ion reduced in Tollens' test

$\text{Ag}^+$ reduced to $\text{Ag}$ (metallic silver)

Reagents that must be freshly prepared

Fehling's and Tollens' reagents

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 Quizzes 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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