Preparation of 0.1 M Perchloric Acid Solutions (HClO4)

Perchloric acid, HClO4, is a strong oxidizing and dehydrating acid commonly used in analytical chemistry and inorganic synthesis. Its preparation and handling require strict adherence to safety protocols. This guide will walk you through the process of preparing a 0.1 M perchloric acid solution in a 50 mL volume, ensuring that all necessary steps are taken to produce a safe and accurate solution.

Materials Needed

Concentrated perchloric acid (usually around 70 w/w with a density of about 1.67 g/mL) Distilled water Volumetric flask or a graduated cylinder (50 mL or larger) Pipette or dropper for precise measurements Safety equipment: gloves, goggles, and a lab coat

Steps for Preparation

Calculate the needed amount of concentrated perchloric acid:

First, determine the molarity you need:

Desired concentration (C2) 0.1 M Desired volume (V2) 50 mL 0.050 L

Use the dilution equation: C1V1 C2V2

Rearranging the equation to solve for volume (V1): V1 (C2V2) / C1.

For the concentrated perchloric acid (approximately 70 w/w):

Density ≈ 1.67 g/mL Molar mass of HClO4 ≈ 100.46 g/mol Concentration (C1) ≈ (70 g/100 mL) * (1 mL/1.67 g) * (1 mol/100.46 g) ≈ 0.42 M

Substitute the values into the equation: V1 (0.1 M * 0.050 L) / 0.42 M ≈ 0.0119 L or 11.9 mL.

Measure the concentrated perchloric acid:

Carefully measure 11.9 mL of concentrated perchloric acid using a pipette or a graduated cylinder. Ensuring precision is crucial for accurate dilution.

Dilute the acid:
In a separate container, preferably a volumetric flask, add approximately 30 mL of distilled water. Slowly add the measured concentrated perchloric acid to the water while stirring continuously. Always add acid to water to prevent the risk of an exothermic reaction and to maintain safety. Make up to volume:

Once the acid is fully mixed with the water, add more distilled water until the total volume reaches 50 mL.

Mix thoroughly:

Ensure the solution is well mixed to achieve homogeneity.

Safety Precautions

Wear appropriate personal protective equipment (PPE): gloves, goggles, and a lab coat. Work in a fume hood or in a well-ventilated area as perchloric acid fumes are hazardous.

Final Note

Label the solution with its concentration (0.1 M) and the date of preparation. Store it properly according to safety guidelines to maintain the integrity and reactivity of the solution.