Which of the following methods is used to form ozone from oxygen?

Silent electric discharge

The correct answer is option 2. Silent electric discharge.

The formation of ozone $(O_3)$ from oxygen $(O_2)$ can be achieved through a process known as silent electric discharge.

Silent electric discharge is a method used to produce ozone from oxygen gas. In this process, oxygen gas $(O_2)$ is passed through a high-voltage electric field at low pressure and low temperature conditions. The electric field causes the oxygen molecules $(O_2)$ to undergo dissociation, breaking them apart into individual oxygen atoms $(O)$. This dissociation occurs due to the impact of high-energy electrons from the electric field, which impart sufficient energy to break the oxygen-oxygen $(O=O)$ bonds in the oxygen molecules. The dissociation reaction can be represented as follows:

$\text{O}_2 \overset{\text{electric discharge}}{\longrightarrow} 2\text{O}$

These highly reactive oxygen atoms $(O)$ then combine with other oxygen molecules $(O_2)$ to form ozone molecules $(O_3)$. The overall reaction for ozone formation can be represented as:

$\text{3O}_2 \overset{\text{electric discharge}}{\longrightarrow} \text{2O}_3$

The term "silent" in silent electric discharge refers to the fact that this method operates at relatively low temperatures and pressures, resulting in minimal noise compared to other forms of electric discharge. The electric field used in silent discharge is typically created using high-voltage electrodes, such as metal wires or plates, placed inside a discharge chamber. The low-pressure conditions help to ensure that the oxygen molecules are uniformly exposed to the electric field, promoting efficient dissociation and ozone formation. The low-temperature conditions prevent excessive heating of the system, which can lead to energy losses and undesirable side reactions.

Silent electric discharge is preferred over other methods for ozone production, such as standard electric discharge, because it operates at lower temperatures and pressures. This method produces higher yields of ozone while consuming less energy, making it more efficient and cost-effective. Silent discharge also allows for better control over the process parameters, resulting in higher purity ozone with fewer unwanted byproducts.

In summary, silent electric discharge is a highly effective method for producing ozone from oxygen gas. It involves passing oxygen gas through a high-voltage electric field at low pressure and temperature conditions, leading to the dissociation of oxygen molecules and subsequent formation of ozone molecules. This process offers several advantages, including higher efficiency, lower energy consumption, and better control over product purity.