Question

Which of the following reaction is used to prepare dihydrogen gas in the laboratory?

• A. \(2Fe_{(s)} + 3H_2O_{(l)}\xrightarrow{\Delta} Fe_2O_{3(s)} + 3H_2(g)\)
• B. \(2Na_{(s)} + 2H_2O_{(l)}\rightarrow 2NaOH_{(aq)} + H_2(g)\)
• C. \(Fe_{(s)} + 2HCl_{(aq)}\rightarrow FeCl_2_{(aq)} + H_2(g)\)
• D. \(Mg_{(s)} + 2H_2O_{(l)}\xrightarrow{\Delta} Mg(OH)_{2(s)} + H_2(g)\)
• E. \(Ca_{(s)} + 2H_2O_{(l)}\rightarrow Ca(OH)_{2(aq)} + H_2(g)\)

Hint:

Granulated zinc is also commonly used with dilute H2SO4 or HCl in a Kipp's apparatus for controlled H2 production.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Laboratory preparation of H2 typically involves reaction of a metal with dilute acid (e.g., Zn/HCl or Fe/HCl).

Step 2: Detailed Explanation:
(A) and (D): Require high temperature, not lab-friendly.
(B) and (E): Violent reaction, not safe for lab prep.
(C): Iron reacts with dilute HCl at room temperature to produce hydrogen gas steadily.

Step 3: Final Answer:
The common lab method is Fe + 2HCl -> FeCl2 + H2.