SMA Kimia - Membuat Larutan Kimia dari Bahan Cair

Summary

This video demonstrates the preparation of a 0.1 Molar NH₄Cl solution from a 1 Molar stock solution. The process involves using a simple dilution formula to calculate the required volume of the stock solution, followed by accurate measurement using a pipette and volumetric flask. The final steps include careful dilution with distilled water and thorough mixing to achieve the desired concentration. This instructional guide emphasizes precision in laboratory techniques, ensuring accurate and reliable solution preparation.

Takeaways

• 😀 The video focuses on the preparation of a diluted solution from a more concentrated stock solution (NH4Cl).
• 😀 The main objective is to dilute a 1 Molar NH4Cl solution to a 0.1 Molar concentration.
• 😀 The dilution process involves taking a measured volume of the concentrated solution and adding water to reach the desired volume.
• 😀 A dilution formula is introduced, where V1 is the volume of the concentrated solution, M1 is its initial concentration, V2 is the final volume, and M2 is the desired concentration.
• 😀 Based on the dilution formula, the required volume to be used from the 1 M solution is calculated as 25 mL.
• 😀 For greater accuracy, a volumetric pipette is recommended over a measuring cylinder for measuring the 25 mL of concentrated solution.
• 😀 The video demonstrates how to transfer the 25 mL of solution into a 250 mL volumetric flask.
• 😀 Once the solution is added to the flask, water is added to bring the total volume up to 250 mL.
• 😀 Precision is important, especially as the liquid level gets close to the 250 mL mark, requiring careful addition using a dropper.
• 😀 After ensuring the solution level is exactly at the 250 mL mark, the flask is sealed and the solution is ready.

Q & A

What is the purpose of the experiment described in the script?

The purpose of the experiment is to demonstrate how to dilute a solution, specifically creating a 0.1 M NH4Cl solution from a 1 M NH4Cl solution.

How is the dilution process conducted?

The dilution process involves taking a known volume of the concentrated NH4Cl solution and adding it to a volumetric flask, then filling the flask with water up to the 250 mL mark to achieve the desired concentration.

What formula is used to determine how much of the concentrated NH4Cl solution is needed?

The dilution formula is used: V1 * M1 = V2 * M2, where V1 is the volume of the concentrated solution, M1 is the initial concentration, V2 is the final volume, and M2 is the final concentration.

How much of the 1 M NH4Cl solution is needed for the dilution?

25 mL of the 1 M NH4Cl solution is needed to prepare the 0.1 M NH4Cl solution.

Why should a volumetric pipette be used instead of a measuring cylinder?

A volumetric pipette should be used for better accuracy when measuring the precise volume of the concentrated NH4Cl solution, especially when dealing with small volumes like 25 mL.

What is the significance of the meniscus in this experiment?

The meniscus is important to ensure accurate measurement when transferring liquids. The volume is measured at the bottom of the meniscus to avoid errors.

What is the role of the volumetric flask in this process?

The volumetric flask is used to mix the solution and precisely control the final volume. It ensures the solution reaches exactly 250 mL for accurate dilution.

Why is it important to add water slowly when nearing the final volume?

It is important to add water slowly and carefully, especially when approaching the 250 mL mark, to avoid overshooting the volume, which could affect the concentration.

What technique is used to mix the solution once it's in the volumetric flask?

After filling the flask with water, the solution is mixed by securing the lid and gently shaking the flask to ensure homogeneity.

What precautions should be taken when preparing the diluted solution?

Precautions include using precise instruments like the volumetric pipette, ensuring the meniscus is correctly observed, and carefully adding water to the flask to avoid exceeding the desired volume.