React phenol with sodium metal
Describe phenol reacting with sodium to produce sodium phenoxide and hydrogen gas.
Section 32 · Hydroxy compounds
A Level; Cambridge International Chemistry 9701, 2028–2030 syllabus, Topic 32. Distinguish phenol (–OH directly on an aromatic ring) from an alcohol (–OH on an aliphatic carbon). Use the specified reagents, temperatures and products; phenol reactions are limited to those listed in the syllabus. Written practice is self-checked
Before you begin
- Recognise alcohols and phenols, aromatic substitution, acids and bases, and diazonium ions from the preceding organic topics.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which gas forms when phenol reacts with sodium metal?
What you will learn
- Recall phenol's reaction with Na(s)
- Write a balanced equation for sodium phenoxide and H₂
- Distinguish sodium metal from aqueous sodium hydroxide
Sodium replaces the acidic hydrogen
Phenol reacts with sodium metal to form sodium phenoxide and hydrogen gas. Sodium replaces the hydrogen on the –OH group; the ring–oxygen bond stays intact.
The balanced equation is 2C₆H₅OH + 2Na → 2C₆H₅ONa + H₂. Two phenol molecules provide the two hydrogen atoms needed for one H₂ molecule.
Match the by-product to the reagent
With sodium metal, hydrogen gas is produced. With aqueous NaOH, water is produced instead. These are different reactions even though both form sodium phenoxide.
Do not write H₂O for the sodium-metal reaction or H₂ for the NaOH neutralisation. Balance the equation before naming the gas.
Pause and explain
How many phenol molecules are needed to balance one H₂ molecule?
Worked example
Balance the reaction between phenol and sodium metal.
Show the worked solution
- Sodium replaces H in the O–H group.
- Make two phenoxide units so two Na atoms are used.
- The two removed H atoms form one H₂ molecule.
Answer 2C₆H₅OH + 2Na → 2C₆H₅ONa + H₂.
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Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Complete and balance the equation C₆H₅OH + Na → …
Give me a hint
Use two O–H hydrogens to form H₂.
Compare my reasoning
- The salt is C₆H₅ONa.
- Use 2 phenol and 2 Na.
- Form one H₂.
2C₆H₅OH + 2Na → 2C₆H₅ONa + H₂.
Look for these in your work
- Salt formula correct
- Coefficients balanced
- Gas identified
Compare the by-products from phenol + Na(s) and phenol + NaOH(aq).
Give me a hint
Match hydrogen metal displacement versus acid-base neutralisation.
Compare my reasoning
- Na(s) gives H₂ gas.
- NaOH(aq) gives H₂O.
- Both produce sodium phenoxide.
Phenol with Na(s) forms sodium phenoxide and H₂; phenol with NaOH(aq) forms sodium phenoxide and H₂O.
Look for these in your work
- Metal reaction products stated
- Hydroxide reaction products stated
- Common salt identified
A balanced equation gives 2C₆H₅OH + 2Na → 2C₆H₅ONa + H₂O. Diagnose the atom/reagent mismatch.
Give me a hint
Check oxygen and hydrogen sources and distinguish water formation.
Compare my reasoning
- No hydroxide or other oxygen source is supplied to form water.
- Sodium metal removes O–H hydrogens as H₂.
- Replace H₂O with H₂.
The by-product should be H₂, not H₂O: 2C₆H₅OH + 2Na → 2C₆H₅ONa + H₂.
Look for these in your work
- Reagent source checked
- Correct gas identified
- Equation corrected
Common mistakes
- Using one phenol molecule but writing H₂
- Writing water as the product
- Placing sodium on the benzene ring
- Calling sodium phenoxide sodium phenol
What can you explain now?
Which gas forms when phenol reacts with sodium metal?
Compare with the explanation
H₂
The O–H hydrogen atoms are released as hydrogen gas.
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Make it stick
How does the sodium-metal reaction differ from phenol neutralisation with NaOH(aq)?
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