Preparation of Alcohol Grades
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How to Prepare 100 mL of 30% Alcohol from 100% Alcohol
How to Prepare 100 mL of 30% Alcohol from 100% Alcohol
Dilution
In the field of genetics, dilution is a fundamental concept and an essential laboratory practice. Most reagents and chemicals are supplied in the form of concentrated stock solutions, which cannot be used directly in experimental procedures. Instead, these stocks must be adjusted to a suitable working concentration, which we defined as "the precise concentration required for a particular assay or protocol". Notably, the working concentration of the same reagent may vary across different experimental applications.
Thus, the process of dilution enables researchers to accurately transform a stock solution into the desired working concentration, ensuring reproducibility and reliability in experimental outcomes. But how can this be done? Here comes a simple and widely used formula:
C₁ V₁ = C₂ V₂
Where:
C₁ = Concentration of the stock solution
V₁ = Volume of the stock solution to be used
C₂ = Desired (working) concentration
V₂ = Final volume of the working solution
Let’s Understand Dilution with an Example: Alcohol Grades
Imagine you have a bottle of pure (100%) alcohol, and you want to prepare 100 mL of a 30% alcohol solution.
Before applying the dilution formula, let’s first understand the meaning of these values:
100% alcohol: This represents the stock concentration, i.e., the original undiluted alcohol.
30% alcohol: This is the working concentration, the strength of alcohol needed for the experiment or application.
100 mL: This is the final volume of solution required. It means that in 100 mL of solution, 30% (30 mL) should be alcohol, and the remaining 70% (70 mL) should be water (or any desired solvent).
In other words, dilution helps us convert the stock concentration (100%) into the desired working concentration (30%) within the required final volume (100 mL).
Step 1: Use the Dilution Formula
C1V1=C2V2
Where:
C1=100% (starting alcohol concentration)
V1=? (volume of alcohol we need to take)
C2=30% (final concentration we want)
V2=100 (total final volume e.g., ml)
Now, plug in the values:
C1V1=C2V2
100%×V1=30%×100ml
V1= 30%×100ml/100%
V1= 30ml (first cancel the % then simply multiply the Numerator: and then divide the value)
This means we need 30 mL of pure alcohol.
Step 2: Add Water to Reach 100 mL
Since we need a total of 100 mL, and we already have 30 mL of alcohol, we need to add:
Total volume required minus (-) calculated working concentration of ur chemical.
100−30=70 mL of water
Step 3: Mix the Solution
Take a measuring cylinder or a measuring flask.
Pour 30 mL of pure alcohol into it.
Slowly add 70 mL of distilled water to it.
Mix well by gently swirling or stirring.
Final Result:
Final Result:
You now have 100 mL of 30% alcohol solution ready to use!
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