Are you working with pure ethanol (100%) and need to dilute it down to a 90% solution? This is a common task in various fields, from laboratories to certain industrial applications. Understanding how to accurately dilute ethanol is crucial to ensure the final concentration is correct and safe. This guide will walk you through the simple calculations and steps needed.
Understanding the Dilution Process
Diluting ethanol involves mixing it with a solvent, usually water, to reduce its concentration. The key principle is maintaining the correct ratio of ethanol to the total volume of the solution. We'll use a simple formula to achieve this.
The Formula: C1V1 = C2V2
This formula is the cornerstone of dilution calculations:
- C1: Initial concentration of ethanol (100%)
- V1: Initial volume of ethanol (the amount you'll start with)
- C2: Final concentration of ethanol (90%)
- V2: Final volume of the diluted solution (the total amount you want to end up with)
Calculating the Dilution
Let's say you want to make 100ml of 90% ethanol. Here's how to calculate the amounts:
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Identify your knowns:
- C1 = 100%
- C2 = 90%
- V2 = 100 ml
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Solve for V1: Rearrange the formula to solve for V1: V1 = (C2V2) / C1
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Plug in the values: V1 = (90% * 100 ml) / 100% = 90 ml
This means you need 90 ml of 100% ethanol.
- Calculate the amount of water: To reach the final volume of 100 ml, you'll need 100 ml (total) - 90 ml (ethanol) = 10 ml of water.
Step-by-Step Dilution Procedure
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Gather your materials: You will need:
- 100% ethanol
- Distilled water (using tap water can introduce impurities)
- Graduated cylinders or other precise measuring devices (avoid using kitchen measuring cups for accuracy)
- A mixing container (glass or plastic are suitable)
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Measure the ethanol: Carefully measure 90 ml of 100% ethanol using a graduated cylinder.
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Add the water: Slowly add 10 ml of distilled water to the ethanol.
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Mix thoroughly: Gently swirl or stir the solution to ensure complete mixing. Avoid vigorous shaking, which could introduce air bubbles.
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Label and store: Clearly label the container with the concentration (90% ethanol), date, and any other relevant information. Store the solution properly according to safety guidelines.
Safety Precautions When Handling Ethanol
- Ethanol is flammable: Keep away from open flames and sparks. Work in a well-ventilated area.
- Ethanol is a volatile substance: Avoid inhaling fumes.
- Wear appropriate safety gear: Gloves and eye protection are recommended.
- Dispose of waste properly: Follow local regulations for disposal of chemical waste.
Scaling Up or Down the Recipe
The formula (C1V1 = C2V2) is easily scalable. If you need a larger or smaller batch of 90% ethanol, simply adjust the volumes while keeping the ratio the same. For example, to make 500ml of 90% ethanol, you would use 450ml of 100% ethanol and 50ml of water.
Remember always prioritize safety when working with chemicals. If you have any concerns about the process, consult a qualified chemist or refer to relevant safety data sheets (SDS) for ethanol.
