A chemical solution consists of 40% acid and the rest water. If 10 liters of water is added to 30 liters of this solution, what is the new percentage of acid in the solution?

Sun, 03 May 2026 14:44:17 +0000

**Understanding Acid Concentration: A Practical Problem with Clear Answers**
When working with chemical solutions, accuracy in concentration matters—especially in industries like manufacturing, pharmaceuticals, and water treatment. A common scenario involves a 40% acid solution, meaning 40% of its volume is pure acid, with the remaining 60% being water. A frequently asked question centers on what happens when water is added: if 10 liters of water are mixed into 30 liters of this 40% acid solution, what percentage of acid remains? This problem isn’t just academic—it reflects real-world applications where dilution significantly impacts performance, safety, and compliance. With growing interest in precision in science and industry, understanding such concentration calculations is more relevant than ever. Why is this question gaining attention in the US? Chemical processes and material safety are under greater scrutiny across sectors. Regulatory bodies and businesses emphasize accurate formulation to ensure safe handling, environmental protection, and product consistency. Additionally, DIY maintenance, home water treatment, and educational trends increasingly bring people face-to-face with concentration chemistry, fueling curiosity about practical outcomes. Let’s break down how a 40% acid solution behaves when water is added. Formulaically, the amount of acid remains constant during dilution—only the total volume changes. Starting with 30 liters of solution at 40% acid, the total acid content is:
30 liters × 0.40 = 12 liters of acid
Adding 10 liters of water gives a total new volume:
30 + 10 = 40 liters
The acid remains at 12 liters, so the new percentage of acid is:
(12 / 40) × 100 = 30%
Natural concentration decreases not because acid vanishes, but because water expands the solution’s total volume—making the acid fraction smaller by volume share alone. This concept resonates across industries: water treatment plants adjust chemical dosages after rainfall; mechanics dilute battery acid solutions; manufacturers check reagent batches. These real-world scenarios highlight why understanding dilutions is essential—not just for experts, but for informed users navigating technical options.