Using the metal activity series, the metal that can liberate hydrogen gas from steam is?

Analysis

The question asks us to identify which of the given metals is reactive enough to displace hydrogen from steam ($H_2O_{(g)}$).

Concept: The Metal Activity Series

The metal activity series (or reactivity series) ranks metals based on their ability to displace hydrogen from water, steam, or acids.

• Highly reactive metals (Potassium, Sodium, Calcium) react vigorously with cold water.
• Moderately reactive metals (Magnesium, Aluminum, Zinc, Iron) react with steam to produce metal oxides and hydrogen gas.
• Less reactive metals (Lead, Copper, Mercury, Silver, Gold) are below hydrogen in the activity series and generally cannot displace hydrogen from water or steam.

The general equation for the reaction of a metal with steam is:

Step-by-Step Solution

1. Evaluate Copper (B): Copper is below hydrogen in the activity series. It is unreactive toward steam.
2. Evaluate Lead (D): Lead is very low in the reactivity series. It does not react with steam.
3. Evaluate Tin (C): While tin is more reactive than lead, it is generally considered to have a very slow or negligible reaction with steam compared to iron.
4. Evaluate Iron (A): Iron is positioned above hydrogen in the activity series. When red-hot iron reacts with steam, it produces tri-iron tetroxide ($Fe_3O_4$) and hydrogen gas: $$3Fe_{(s)} + 4H_2O_{(g)} \rightarrow Fe_3O_4(s) + 4H_2(g)$$ This is a classic reaction taught in Nigerian secondary school chemistry curricula.

Conclusion

Among the options provided, iron is the only metal that effectively reacts with steam to liberate hydrogen gas.

Exam Tip

Remember the mnemonic for the reactivity series: Please Stop Calling Me A Careless Zebra Instead Try Learning How Copper Saves Gold. (Potassium, Sodium, Calcium, Magnesium, Aluminum, Carbon, Zinc, Iron, Tin, Lead, Hydrogen, Copper, Silver, Gold). Anything above Hydrogen can displace it from acids, but only those from Magnesium up to Iron react readily with steam!