Question

Describe the bulk preparation of dihydrogen by electrolytic method. What is the role of an electrolyte in this process?

Short answer

The electrolyte enhances the conductivity of water, facilitating hydrogen production through electrolysis.

Step-by-step solution

Understand Dihydrogen Production

The bulk preparation of dihydrogen can be achieved through the electrolytic method, which involves the decomposition of water into hydrogen and oxygen gases using electricity.

Set Up the Electrolytic Cell

To set up the electrolytic cell, you will need two electrodes (an anode and a cathode) immersed in water, which serves as the electrolyte. The electrodes are typically made of inert materials such as platinum or graphite to avoid corrosion and unwanted reactions.

Add Electrolyte

An electrolyte such as an acid (sulfuric acid, H2SO4) or a base (sodium hydroxide, NaOH) is added to the water to improve its conductivity. Pure water is a poor conductor of electricity, so adding the electrolyte facilitates the flow of electric current.

Apply Electric Current

When a direct electric current is applied across the electrodes, water molecules undergo electrolysis. At the cathode, water is reduced to form hydrogen gas: \[ 2H_2O + 2e^- ightarrow H_2 + 2OH^- \]

Understanding the Role of the Electrolyte

The role of the electrolyte is crucial as it dissociates in the water to produce ions. These ions conduct electricity, allowing the electrolytic process to occur efficiently. This enables hydrogen ions to collect electrons at the cathode to produce dihydrogen.

Key concepts

Electrolysis

Electrolysis is a chemical process wherein an electric current is used to induce a chemical reaction which otherwise does not occur spontaneously. It is a vital technique for breaking down compounds into their elements or other simpler molecules. In the context of dihydrogen production, water is decomposed into hydrogen and oxygen gases through electrolysis. This process requires the electrical input, as the water molecule is stable and needs energy to initiate its decomposition. By passing electricity through the water, hydrogen ions at the cathode and oxygen ions at the anode are formed, producing dihydrogen and dioxygen, respectively. Understanding electrolysis is essential for mastering the electrolytic preparation of dihydrogen.

Role of Electrolyte

An electrolyte plays a critical role in the electrolytic production of dihydrogen by acting as a medium for current flow. Typically, water is used as the solvent, but pure water is a poor conductor of electricity. By adding an electrolyte like sulfuric acid (H₂SO₄) or sodium hydroxide (NaOH), the conductivity of the water is greatly improved.

The presence of the electrolyte increases the number of ions in the solution, which are vital for conducting electricity. These ions carry the electric current between electrodes, facilitating the water decomposition into hydrogen and oxygen. The effective functioning of this process largely depends on the proper selection and concentration of the electrolyte.

Electrolytic Cell Setup

Setting up an electrolytic cell for the production of dihydrogen is straightforward, yet it needs precision and care to ensure efficiency. This setup involves immersing two electrodes in an electrolyte solution. The materials for the electrodes are typically inert to prevent any unwanted side reactions. Common choices are platinum or graphite.

The cell is connected to a source of direct current (DC) electricity. Upon application of the electric current, the setup becomes active with the anode and cathode facilitating the flow of electrons. While the cathode facilitates hydrogen ion reduction to form dihydrogen, the anode supports the oxidation of hydroxide ions, producing oxygen gas.

Water Decomposition

In electrolytic dihydrogen production, water's decomposition is central to the process. When electricity is introduced to water with dissolved electrolyte, the water molecules dissociate into ions: hydrogen ions (H^+) and hydroxide ions (OH^−).

At the cathode, hydrogen ions gain electrons (e^−) to form hydrogen gas (H_2), while at the anode, hydroxide ions release electrons to form oxygen gas (O_2). This chemical reaction is represented by the following equation at the cathode: \(2H_2O + 2e^- \rightarrow H_2 + 2OH^-\). The balanced decomposition of water ensures that both gases are produced in equal molar quantities, highlighting the efficiency of the electrolytic method.

Hydrogen Gas Production

The ultimate goal of electrolytic water decomposition is hydrogen gas production. At the cathode, where hydrogen ions congregate, they gain electrons from the electric current and form hydrogen gas. This hydrogen gas bubbles out of the solution and can be collected for various uses.

The efficiency of hydrogen production in this process is governed by several factors, including the quality and concentration of the electrolyte, the material and surface area of the electrodes, and the voltage applied. This process is environmentally friendly as it only splits water into its elemental components without producing any harmful byproducts. Understanding each part of hydrogen production helps in scaling the process for industrial applications and achieving sustainable energy solutions.