Q1: Which of the following is the costliest method for commercial production of hydrogen for ammonia synthesis ?

ANS:D - Electrolysis of water

The costliest method for the commercial production of hydrogen for ammonia synthesis among the options provided is typically: Electrolysis of water. Electrolysis of water involves the use of electricity to split water molecules into hydrogen and oxygen gases. This method can be energy-intensive and therefore expensive, especially if the electricity used is derived from non-renewable sources. Additionally, the electrolysis process may require sophisticated equipment and infrastructure, further contributing to its cost. In contrast, the other methods listed—H2 separation from coke oven gas, steam reforming of naphtha, and cracking of natural gas—are generally more cost-effective for large-scale commercial hydrogen production, as they utilize feedstocks such as hydrocarbons or industrial byproducts that are abundant and relatively inexpensive. So, the correct option is: Electrolysis of water. Electrolysis of water is a chemical process that uses electricity to split water molecules (H2O) into hydrogen gas (H2) and oxygen gas (O2). It involves passing an electric current through water, which causes the water molecules to undergo a decomposition reaction, releasing hydrogen and oxygen gases. The electrolysis of water takes place in an electrolysis cell, which typically consists of two electrodes—an anode and a cathode—immersed in a container of water containing an electrolyte (usually a small amount of acid or base to enhance conductivity). When an electric current is applied to the electrodes, the following reactions occur at each electrode:

1. At the Anode (Positive Electrode): At the anode, oxidation occurs, leading to the production of oxygen gas and positively charged hydrogen ions (protons): 2𝐻2𝑂(𝑙)→𝑂2(𝑔)+4𝐻+(𝑎𝑞)+4𝑒−2H2​O(l)→O2​(g)+4H+(aq)+4e−
2. At the Cathode (Negative Electrode): At the cathode, reduction occurs, causing the hydrogen ions to gain electrons and form hydrogen gas: 4𝐻+(𝑎𝑞)+4𝑒−→2𝐻2(𝑔)4H+(aq)+4e−→2H2​(g)

Overall, the electrolysis of water can be represented by the following overall equation: 2𝐻2𝑂(𝑙)→2𝐻2(𝑔)+𝑂2(𝑔)2H2​O(l)→2H2​(g)+O2​(g) The hydrogen gas produced through electrolysis of water can be collected and used as a clean and renewable source of energy for various applications, including fuel cells, transportation, and industrial processes. Additionally, the oxygen gas generated can be used for various purposes, such as industrial processes or medical applications. While electrolysis of water offers a clean and sustainable method for hydrogen production, it can be energy-intensive and therefore expensive, especially if the electricity used is derived from non-renewable sources. However, advancements in electrolysis technology, along with the use of renewable energy sources such as solar or wind power, are helping to make electrolysis of water more economically viable as a method for hydrogen production.