A chemist mixes 5.2 liters of Solution A with 3.8 liters of Solution B. If Solution A contains 15% acid and Solution B contains 25% acid, what is the concentration of acid in the resulting mixture? - Parker Core Knowledge

Understanding the Context

Why This Mixture Is Gaining Attention in the U.S.

Recent discussions among chemistry professionals, educators, and industry groups point to rising focus on accurate solution blending, especially as new regulations emphasize precise chemical handling and traceability. The practical application of mixing known volumes and percentages supports safer lab environments, better-polished industrial outputs, and more reliable educational demonstrations.

Additionally, with increasing public awareness around chemical safety and environmental monitoring, understanding how concentration shifts during mixing supports informed decisions in waste management, research, and educational outreach—opening pathways for broader engagement beyond academia.

Key Insights

How to Calculate Acid Concentration in Mixed Solutions

When combining solutions of different acid concentrations, the final concentration isn’t simply the average of the two percentages. Instead, it’s found by calculating a weighted average based on volume and acid content.

Start by determining how much pure acid each solution contributes. For Solution A (5.2 liters at 15% acid), multiply:
5.2 L × 0.15 = 0.78 liters of acid

For Solution B (3.8 liters at 25% acid):
3.8 L × 0.25 = 0.95 liters of acid

Final Thoughts

Next, sum the total acid:
0.78 + 0.95 = 1.73 liters

Then, add the total volume of the mixed solution:
5.2 + 3.8 = 9.0 liters

Finally, divide total acid by total volume:
1.73 ÷ 9.0 ≈ 0.1922

Convert to percentage: 0.1922 × 100 ≈ 19.22%

Thus, the resulting mixture contains about 19.2% acid—a precise blend that reflects deliberate, science-backed mixing.