Ethanol is a member of the alcohol family of compounds. Explain what happens when a small piece of sodium metal is added to a sample of ethanol, and describe how the products of this reaction can be identified.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Ethanol (C₂H₅OH) reacts with sodium metal in a similar way to how sodium reacts with water. The reaction produces a gas and a solution containing ionic products.
Model answer (5 marks)
Sodium reacts with ethanol, giving off hydrogen gas and forming sodium ethoxide:
Na + C₂H₅OH → NaOEt + ½ H₂↑
The hydrogen gas can be identified by the squeaky pop test – hold a lit splint to the gas; it makes a sharp pop.
The sodium ethoxide can be confirmed by a flame test: a sample of the solution (or solid residue) gives a bright yellow/orange flame, indicating the presence of Na⁺ ions.
Na + C₂H₅OH → NaOEt + ½ H₂↑
The hydrogen gas can be identified by the squeaky pop test – hold a lit splint to the gas; it makes a sharp pop.
The sodium ethoxide can be confirmed by a flame test: a sample of the solution (or solid residue) gives a bright yellow/orange flame, indicating the presence of Na⁺ ions.
Examiner tips
- Show the balanced equation and state the gas produced; use the pop test to identify H₂.
- Mention the flame test for Na⁺ to confirm sodium ethoxide.
- Use correct chemical symbols and units.
Common mistakes
- Writing the reaction as Na + C₂H₅OH → NaOEt + H₂ (missing stoichiometry).
- Failing to identify the gas as H₂ or not describing the pop test.
- Confusing sodium ethoxide with sodium hydroxide or not mentioning the flame test.
Mark scheme (5 marks)
- Sodium reacts with ethanol / a reaction takes place
- Hydrogen gas is produced / given off
- Sodium ethoxide (an ionic salt / sodium salt of ethanol) is also formed as a product
- The gas can be identified by holding a lit splint to it / the squeaky pop test
- A flame test could be used on the solution / solid residue to confirm the presence of sodium ions, giving a yellow/orange flame
Key terms in this question
Related
- All OCR A-Level Chemistry A (H432) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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