When diluting acids, what important precaution should be followed?

When diluting acids, what important precaution should be followed?

• A. Add water to the acid slowly.
• B. Add the acid to the water slowly.
• C. Mix acids and water rapidly to speed up the reaction.
• D. Use hot water for faster dilution.

Answer: (B)

The key idea is safety during dilution of acids: the process releases a lot of heat (exothermic), so you must control the heat and prevent splattering. Adding the acid to water slowly allows the heat to dissipate gradually in the larger volume, reducing the chance of the mixture boiling or spraying acid back at you. This slow, controlled approach keeps the reaction safer and more manageable. Pouring water into concentrated acid is dangerous because the heat can cause rapid boiling and splattering, creating a hot, acidic spray. Rushing the mixing or trying to speed things up with rapid stirring or with hot water only increases the risk, so those practices are not appropriate. The safer, correct method is to add the acid to the water slowly and with stirring, maintaining control over the temperature rise.

The key idea is safety during dilution of acids: the process releases a lot of heat (exothermic), so you must control the heat and prevent splattering. Adding the acid to water slowly allows the heat to dissipate gradually in the larger volume, reducing the chance of the mixture boiling or spraying acid back at you. This slow, controlled approach keeps the reaction safer and more manageable.

Pouring water into concentrated acid is dangerous because the heat can cause rapid boiling and splattering, creating a hot, acidic spray. Rushing the mixing or trying to speed things up with rapid stirring or with hot water only increases the risk, so those practices are not appropriate. The safer, correct method is to add the acid to the water slowly and with stirring, maintaining control over the temperature rise.