When preparing an acid solution, what is the recommended order of mixing water and acid?

When preparing an acid solution, what is the recommended order of mixing water and acid?

• A. Always add acid to 2/3 water, then add rest of water
• B. Add water to acid until fully mixed
• C. Add acid to water after boiling
• D. Mix acid and water in any order

Answer: (A)

The key idea is safety when diluting acids: the mixing releases a lot of heat, so add acid to water gradually rather than pouring water into concentrated acid. Start with about two-thirds of the total water in the container, slowly pour the acid into the water while stirring, then add the remaining water to reach the final mixture. This stepwise approach lets the water absorb the heat as it’s produced, reducing the risk of the solution getting too hot, boiling, or splattering. Adding water to acid or mixing in any order without a controlled sequence can lead to dangerous, rapid heat release and accidents.

The key idea is safety when diluting acids: the mixing releases a lot of heat, so add acid to water gradually rather than pouring water into concentrated acid. Start with about two-thirds of the total water in the container, slowly pour the acid into the water while stirring, then add the remaining water to reach the final mixture. This stepwise approach lets the water absorb the heat as it’s produced, reducing the risk of the solution getting too hot, boiling, or splattering. Adding water to acid or mixing in any order without a controlled sequence can lead to dangerous, rapid heat release and accidents.