Steam and Hot Metals
See how steam reacts with heated metals like iron and zinc.
What this lesson covers
Why it matters
Pass steam over red-hot iron and listen for the pop of hydrogen gas. The metal darkens as it trades electrons with water vapour.
The idea in plain words
Balance iron + steam yourself. Fe₃O₄ locks three iron atoms and four oxygens into one magnetic oxide — set the coefficients so every atom is accounted for, and notice the ⇌ sign: this reaction can run backwards.
Predict first
What gas is produced when steam reacts with heated metals like Mg, Zn, or Fe?
The metal displaces hydrogen from water. The gas collected burns with a pop, confirming it is hydrogen.
- Oxygen
- Hydrogen — correct
- Carbon dioxide
- Water vapour
What you do
Heat the metals strongly and pass steam over them. Observe the solid residue and test the gas evolved.
Check yourself
What is observed when steam reacts with heated zinc?
Zn + H₂O → ZnO + H₂. ZnO is yellow when hot and white when cold. The gas pops with a burning splinter.
Why does the reaction of iron with steam require red-hot conditions?
Iron is lower in the reactivity series than Mg or Zn, so it requires higher energy (red-hot) to displace hydrogen from steam.
What is the product formed on the surface of magnesium after reaction with steam?
Mg + H₂O → MgO + H₂. With steam, magnesium oxide (white solid) is formed, not hydroxide.
- White residue and hydrogen gas — correct
- Black residue and oxygen gas
- No reaction occurs
- Iron is less reactive than magnesium or zinc — correct
- Iron is magnetic
- Steam needs to be liquid to react
- To produce carbon dioxide
- Magnesium hydroxide
- Magnesium oxide — correct
- Magnesium carbonate