Consider the following statements:
While diluting concentrated nitric acid solution
- the concentration of [H3O+] ions/ volume increases
- water must be added slowly to concentrated acid
- acid must be added slowly to water
Which of the statements given above is/are correct?
1, 2 and 3
1 and 2 only
3 only
2 and 3 only
Answer is Wrong!
Answer is Right!
This question was previously asked in
UPSC CDS-1 – 2023
1. the concentration of [H₃O⁺] ions/ volume increases: When diluting a concentrated acid by adding water, the *volume* of the solution increases significantly. While the total amount of H₃O⁺ ions might increase slightly due to more complete ionization in a more dilute solution, the increase in volume is much larger, leading to a *decrease* in the concentration of H₃O⁺ ions per unit volume. This statement is incorrect.
2. water must be added slowly to concentrated acid: Adding water to concentrated acid is a highly exothermic process. Adding water directly to concentrated acid can generate a large amount of heat rapidly, causing the water to boil and potentially splash corrosive acid out of the container. This is a dangerous procedure. This statement is incorrect.
3. acid must be added slowly to water: The correct and safe way to dilute concentrated acid is to add the concentrated acid slowly, drop by drop, to a large volume of water while stirring constantly. This method allows the heat generated by the exothermic reaction to be absorbed by the larger volume of water, preventing dangerous temperature increases and splashing. This statement is correct.
Based on the analysis, only statement 3 is correct.
– Always add acid to water, not water to acid, for safety.
– Dilution decreases the concentration of hydronium ions.