Question 1

Does C1V1 = C2V2 work for all types of solutions?

Accepted Answer

This equation works well for dilute and ideal solutions where volumes are additive. It may be inaccurate for highly concentrated solutions, mixtures with significant volume changes on mixing (e.g., ethanol-water), or solutions where solute-solvent interactions change with concentration.

Question 2

Should I add acid to water or water to acid?

Accepted Answer

Always add acid to water ("do as you oughta, add acid to water"). Adding water to concentrated acid can cause localized boiling and violent spattering due to the large exothermic heat of dilution. Slowly add the concentrated acid to the water while stirring to distribute heat safely.