Diluting a Concentrated Acid: A Chemist's Guide to Creating 3.5 M HCl from 14.0 M HCl

Chemists often need to prepare specific concentrations of solutions for their experiments. In this article, we will guide you through the process of diluting a highly concentrated 14.0 M hydrochloric acid (HCl) solution to make 600.0 mL of a 3.5 M HCl solution. We will use the dilution equation, ensure safety measures, and provide step-by-step instructions to perform this task accurately.

The Dilution Equation and Its Application

The dilution equation is a fundamental concept in chemistry, allowing us to determine the volume of a concentrated solution needed to achieve a desired concentration. The formula used is:

C1V1 C2V2

Where:

C1 Initial concentration (14.0 M) V1 Volume of the concentrated solution needed C2 Final concentration (3.5 M) V2 Final volume (600.0 mL)

Step-by-Step Procedure

Convert volume from mL to L:

V2 600.0 mL 0.600 L

Solve for V1:

Equation Rearrangement:

V1 frac{C2V2}{C1}

Substitute the known values:

V1 frac{3.5 M times 0.600 L}{14.0 M} 0.150 L 150.0 mL

Prepare the diluted solution: Measure 150.0 mL of the 14.0 M HCl solution. Transfer this volume into a 600.0 mL volumetric flask or a suitable container. Add distilled water to the flask until the total volume reaches 600.0 mL.

Important Safety Notes

When diluting concentrated acids:

Always add acid to water, not water to acid to prevent exothermic reactions that can cause splattering. Wear appropriate personal protective equipment (PPE) such as gloves and goggles when handling strong acids.

Advanced Dilution Technique

For a more practical and controlled method, you can follow these additional steps:

Determine the volume of the more concentrated stock solution:

14.0 M V1 3.50 M times 600.0 mL

V1 frac{3.50 M times 600.0 mL}{14.0 M} 150 mL HCl

Prepare the solution: Carefully measure out 150.0 mL of the stock HCl solution. Add a small amount of water (~100 mL) to a 1.0 L beaker or volumetric flask. Slowly and with stirring, add the 150 mL of HCl to the water in the beaker or volumetric flask. When the solution has cooled, add the remaining 50.0 mL of water to reach the 600.0 mL mark. Stopper the flask and invert several times to thoroughly mix the solution.

Always remember the important safety note: never add water directly to a concentrated acid, as this process generates a significant amount of heat that may cause the acid to boil and spatter. Adding a small volume of water to the acid first allows the heat to be absorbed, preventing splattering and ensuring safety.