Preparing a 30% by Weight Solution of Sulfuric Acid: A Comprehensive Guide

To prepare a 30% by weight (w/w) solution of sulfuric acid (H2SO4), it is essential to mix sulfuric acid with water in the correct proportions. This guide will walk you through the process step-by-step, ensuring you achieve a safe and accurate solution.

Materials Needed

Concentrated sulfuric acid typically around 98% pure Distilled water A balance to measure weight A graduated cylinder or volumetric flask Protective gear: gloves, goggles, and a lab coat

Calculation

For a 30% w/w solution, you need 30 grams of sulfuric acid for every 100 grams of solution. Here is a detailed calculation:

Determine the Mass of the Solution

Decide how much solution you want to prepare. For example, if you want to make 1 liter (1000 grams) of a solution: Total mass of solution 1000 grams Mass of sulfuric acid 30% of 1000 grams 300 grams Mass of water Total mass - Mass of sulfuric acid 1000 grams - 300 grams 700 grams

Using Concentrated Sulfuric Acid

Since concentrated sulfuric acid is approximately 98% pure, you need to account for this:

Actual mass of concentrated sulfuric acid required mass of pure sulfuric acid / purity Actual mass 300 grams / 0.98 ≈ 306.12 grams of concentrated sulfuric acid

Preparation Steps

Measure the Ingredients

Weigh out approximately 306.12 grams of concentrated sulfuric acid Weigh 700 grams of distilled water

Add Acid to Water

IMPORTANT:

Always add strong acids like sulfuric acid to water, never the other way around. This prevents exothermic reactions that can cause splattering. Slowly pour the measured sulfuric acid into the water while stirring continuously. This helps dissipate heat and ensures thorough mixing.

Cooling

Allow the solution to cool if it becomes warm during mixing.

Transfer and Store

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

Safety Precautions

Always wear appropriate personal protective equipment (PPE): gloves, goggles, and a lab coat. Work in a well-ventilated area or under a fume hood. Be cautious of the heat generated during the mixing process.

Conclusion

Following these steps will yield a 30% by weight sulfuric acid solution. Adjust the quantities based on your needs, ensuring you maintain the 30:70 ratio by weight.

Incorporating this detailed process into your laboratory procedures can help ensure the accuracy and safety of your chemical solutions. Proper adherence to these guidelines is crucial for any chemistry experiment or industrial application involving sulfuric acid.