A virologist is designing an experiment where she needs to prepare 120 mL of a 10% saline solution. She has a stock solution of 25% saline. How many milliliters of the stock solution does she need to use, and how much water should she add to achieve the desired concentration? - Treasure Valley Movers

A virologist is designing an experiment where she needs to prepare 120 mL of a 10% saline solution. She has a stock solution of 25% saline. How many milliliters of the stock solution does she need to use, and how much water should she add to achieve the desired concentration?
This challenge is gaining attention in scientific and lab communities across the U.S., as accurate saline preparation is essential for consistent experimental results and patient safety. When working with concentrated stock solutions, precise dilution ensures reliability—critical when variables like concentration directly impact research outcomes.

Why This Calculation Matters Now

In academic and clinical settings, saline solutions are foundational in laboratories, diagnostics, and medical protocols. The ability to reliably dilute a stock solution to a target concentration—like 10% for cell culture media or solution buffers—reflects fundamental knowledge in scientific workflow management. As research accuracy grows more central, even routine steps like saline preparation become key points of focus for maintaining reproducibility. For professionals and students alike, mastering this ratio ensures readiness and precision.

How to Dilute the Stock Solution Safely

To create 120 mL of a 10% saline solution from a 25% stock, begin with an exact volume of the concentrated solution. Using the dilution formula (C₁V₁ = C₂V₂), rearrange to find the needed stock volume:

V₁ = (C₂ × V₂) / C₁ = (10% × 120 mL) / 25% = 48 mL

She needs 48 mL of the 25% stock solution.

To reach the final volume, add water until the total reaches 120 mL. That means adding:

120 mL – 48 mL = 72 mL of distilled or deionized water

Common Questions About Dilution

What if I only need a precise concentration?

You can achieve exact percentages by measuring volume precisely—no estimation needed. This accuracy supports reliable experimental design.

Can I use tap water instead of distilled?

While acceptable for many lab settings, distilled water reduces contamination risk and ensures purity. For sensitive experiments, purified water is preferred.

Does temperature affect the concentration?

Saline concentration