Preparation of a 20% Sulfuric Acid Solution: A Guide for Chemists and Lab Technicians

Harmonizing safety with precision, this article provides a comprehensive guide on preparing a 20% sulfuric acid solution, a crucial standard in industrial and laboratory applications. This guide is ideal for chemists, lab technicians, and anyone involved in the safe handling of sulfuric acid solutions.

Materials Needed

Concentrated sulfuric acid (typically 98% concentration) Distilled water Safety equipment: Gloves Goggles Lab coat A graduated cylinder or volumetric flask A mixing container (beaker) A stirring rod

Calculation

Determine the Volume of Solution Needed

Decide how much 20% sulfuric acid solution is required. For demonstration, let's assume we need 100 mL of the solution.

Calculate the Amount of Concentrated Acid

A 20% solution means that 20 g of sulfuric acid are present in 100 mL of the solution. The density of concentrated sulfuric acid is approximately 1.84 g/mL.

The calculation involves two steps:

Calculate the mass of concentrated sulfuric acid needed:

[ text{Mass of concentrated acid} frac{text{Mass of sulfuric acid}}{text{Concentration}} frac{20 text{ g}}{0.98} approx 20.41 text{ g} ]

Convert this mass to volume:

[ text{Volume of concentrated acid} frac{text{Mass}}{text{Density}} frac{20.41 text{ g}}{1.84 text{ g/mL}} approx 11.09 text{ mL} ]

Calculate the Amount of Water

To make 100 mL of solution, subtract the volume of concentrated acid from the total volume:

[ text{Volume of water} 100 text{ mL} - 11.09 text{ mL} approx 88.91 text{ mL} ]

Procedure

Safety First

Wear gloves, goggles, and protective clothing. Work in a well-ventilated area or under a fume hood.

Add Water to Container

Measure approximately 88.91 mL of distilled water in a beaker.

Add Concentrated Acid

Slowly add 11.09 mL of concentrated sulfuric acid to the water. Always add acid to water, never water to acid, as adding water to concentrated acid can cause violent reactions and splattering.

Mix Carefully

Stir the solution gently with a stirring rod to ensure thorough mixing. The solution will heat up due to the exothermic reaction.

Cool if Necessary

Allow the solution to cool if it becomes too warm.

Transfer to Storage Container

Once mixed and cooled, transfer the solution to a labeled storage container.

Final Notes

Always handle sulfuric acid with care and dispose of any waste according to local regulations. Ensure proper labeling of the solution and store it safely.

ProTip: This method will yield a 20% sulfuric acid solution suitable for various applications, ensuring accuracy and safety in your laboratory or industrial processes.

Keywords: sulfuric acid, 20% solution, laboratory preparation