Chemistry Q132 – AP-EAMCET 2026

Home Chemistry Basic ChemistryQuestion #13

High purity (

> 99.95 %

) dihydrogen is obtained by the process

Clue 1 of 3: Hydrogen Production Methods

Different industrial methods are used to produce hydrogen, each yielding varying levels of purity.

🧠 Full Solution Path

Step 1: Understand the Requirement✦ Active

The question asks for a method to produce dihydrogen ( $H_{2}$ ) with a very high purity, specifically greater than $99.95 %$ . This implies that we need to select a process known for yielding extremely pure hydrogen, often through electrolysis with specific electrolytes.

💡 Teacher's Secret Hint

Always pay attention to quantitative requirements like purity levels, as they often differentiate between technically similar processes.

Step 2: Evaluate Industrial Hydrogen Production Methods○ Expand

Let's examine the common industrial methods for hydrogen production mentioned in the options:

1. **Steam reforming of methane (Option 3):** This process, ${CH}_{4} (g) + H_{2} O (g) \overset{Ni catalyst, 1270 K}{\to} CO (g) + 3 H_{2} (g)$ , produces 'synthesis gas' (a mixture of $CO$ and $H_{2}$ ). While a major source of hydrogen, the product requires extensive purification steps (like water-gas shift reaction and pressure swing adsorption) to achieve very high purity, and the initial gas mixture is not $> 99.95 %$ pure $H_{2}$ .

2. **Coal gasification (Option 4):** Similar to steam reforming, $C (s) + H_{2} O (g) \overset{high temp}{\to} CO (g) + H_{2} (g)$ , produces syngas. The hydrogen obtained from this process also requires significant purification to reach high purity levels.

3. **Electrolysis of brine solution using Nelson cell (Option 2):** This chlor-alkali process, $2 NaCl (a q) + 2 H_{2} O (l) \overset{electrolysis}{\to} 2 NaOH (a q) + {Cl}_{2} (g) + H_{2} (g)$ , produces hydrogen along with chlorine gas. The hydrogen produced can be contaminated with chlorine, making it unsuitable for very high purity applications without further extensive separation.

Step 3: Analyze Electrolysis of Warm Barium Hydroxide○ Expand

The **electrolysis of warm ${Ba(OH)}_{2}$ solution using nickel electrodes (Option 1)** is a specific method known for producing extremely pure dihydrogen. Barium hydroxide ( ${Ba(OH)}_{2}$ ) acts as a stable electrolyte that provides ions for conductivity in the water, without introducing volatile byproducts that would contaminate the hydrogen.

The overall reaction is the electrolysis of water:

2 H_{2} O (l) \overset{electrolysis}{\to} 2 H_{2} (g) + O_{2} (g)

Because ${Ba(OH)}_{2}$ is non-volatile and stable, the gaseous hydrogen collected is typically of very high purity, often exceeding $99.95 %$ .

💡 Teacher's Secret Hint

Electrolysis of water using a non-interfering electrolyte like ${Ba(OH)}_{2}$ or $KOH$ is ideal for high-purity hydrogen production, as the only gaseous products are hydrogen and oxygen, which can be easily separated.

Step 4: Conclusion○ Expand

Comparing the methods, the electrolysis of warm ${Ba(OH)}_{2}$ solution is the most appropriate process for obtaining high purity (> $99.95 %$ ) dihydrogen.

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Chemistry Question 132 – AP-EAMCET 2026

Clue 1 of 3: Hydrogen Production Methods

🧠 Full Solution Path