Introduction:
When diluting acid, it is important to add acid to water rather than water to acid. This process is called dilution, and it is crucial to follow this specific order to ensure safety and prevent accidents. Adding water to acid can result in a violent reaction, leading to dangerous splattering and potential harm. Understanding the reasons behind this procedure is essential for any individual working with acids.

1. Safety:
The primary reason for adding acid to water is safety. When water is added to acid, it can cause an exothermic reaction, releasing a significant amount of heat. This rapid heat generation can cause the mixture to boil and produce steam, leading to the ejection of acid droplets. These droplets can cause severe burns and injuries if they come into contact with the skin or eyes. By adding acid to water slowly, the heat is dissipated more effectively, reducing the risk of splattering.

2. Control:
Adding acid to water allows for better control over the reaction. When acid is poured into water, the mixture can be stirred continuously, ensuring a thorough and even dilution. This method prevents localized concentrations of acid, which may lead to unexpected reactions. Additionally, the slow addition of acid to water allows for monitoring and adjustment if necessary.

3. Dilution Process:
The dilution process involves adding a concentrated solution of acid to a larger volume of water. By pouring acid into water, the initial volume is smaller, reducing the risk of overflow. This approach also minimizes the chances of creating an excessive concentration of acid, which could potentially lead to a more vigorous reaction.

4. Chemical Reaction:
When water is added to acid, the reaction can become highly exothermic due to the high concentration of acid. The energy released during this process can cause the mixture to rapidly heat up and boil, leading to hazardous consequences. By adding acid to water, the reaction is more controlled, allowing for a gradual temperature increase and dissipation of heat.

Conclusion:
Adding acid to water rather than water to acid is a crucial safety measure. This method ensures safety by preventing violent reactions, offering better control over the dilution process, and minimizing the risk of burns or injuries. Understanding and following this procedure is essential for anyone working with acids to maintain a safe working environment.

We should always add acid in water because when we dilute acid heat is evolved and if we add water in acid then the heat evolved is too much that an accident will take place in laboratory and we will get burnt also. That's why it is suggested to add acid in water amd not water in acid