Making a precise dilution of ethanol requires careful measurement and understanding of concentration. This guide will walk you through the process of diluting 100% ethanol to achieve a 90% concentration. It's crucial to remember safety precautions when handling ethanol, as it's highly flammable. Always work in a well-ventilated area, away from open flames.
Understanding the Dilution Process
The core principle behind dilution is to reduce the concentration of a solute (in this case, ethanol) by adding a solvent (typically water). We'll use a simple formula to calculate the required amounts:
C1V1 = C2V2
Where:
- C1 is the initial concentration of ethanol (100%)
- V1 is the initial volume of ethanol (this is what we'll need to determine)
- C2 is the final concentration of ethanol (90%)
- V2 is the final volume of the solution (this is the total volume you want to end up with)
Calculating the Required Amounts
Let's say you want to make 1000ml (1 liter) of 90% ethanol solution. We can plug these values into our formula:
100% * V1 = 90% * 1000ml
Solving for V1:
V1 = (90% * 1000ml) / 100% = 900ml
This means you need 900ml of 100% ethanol. To achieve a final volume of 1000ml, you'll need to add 100ml of water (1000ml - 900ml = 100ml).
Step-by-Step Dilution Process
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Gather your materials: You will need a 1000ml volumetric flask (or another suitable graduated container with accurate markings), a graduated cylinder or pipette for precise measurements, 100% ethanol, distilled water, and safety glasses. Using distilled water is important to ensure purity and avoid the introduction of unwanted substances.
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Calculate the required volumes: Use the formula above to calculate the necessary volume of ethanol and water based on your desired final volume. It's always a good idea to double-check your calculations before proceeding.
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Add the ethanol: Carefully pour the calculated volume of 100% ethanol into the volumetric flask.
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Add the water: Slowly add the calculated volume of distilled water to the flask. Adding water slowly helps prevent splashing and ensures a more accurate mixture.
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Mix thoroughly: Gently swirl the flask to ensure the ethanol and water are thoroughly mixed. Avoid shaking vigorously to prevent foaming or splashing.
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Check the volume: Ensure the final volume reaches the 1000ml mark on your volumetric flask. If necessary, carefully add more water to adjust the volume.
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Label the solution: Clearly label the solution with its concentration (90% ethanol) and date of preparation.
Safety Precautions
- Always wear safety glasses when handling ethanol.
- Work in a well-ventilated area. Ethanol fumes are flammable and can be intoxicating.
- Keep away from open flames and ignition sources.
- Handle ethanol with care to avoid spills and skin contact.
- Dispose of ethanol properly according to local regulations.
Variations and Considerations
This method can be scaled up or down to produce different quantities of 90% ethanol solution. Simply adjust the V2 value in the formula to match your desired final volume and recalculate V1. Remember to always maintain precise measurements for accuracy.
By following these steps, you can safely and accurately dilute 100% ethanol to achieve a 90% solution. Always prioritize safety when working with chemicals.
