Praktikum Kesadahan Pada Air

Summary

This video demonstrates a simple method for testing water hardness using a chemical titration process. The procedure involves measuring a 100 ml water sample, adding pH indicator and EDTA solution, and performing a titration to determine the water’s hardness. The test observes changes in color, from dark red to sea blue, to assess the water's mineral content. Key safety precautions, such as wearing gloves and masks, are highlighted. The video also explains the calculation for total hardness using a formula based on the volume of titrant used and the molar mass of calcium carbonate.

Takeaways

• 😀 Always wear gloves and a mask when performing the water hardness test to protect yourself from chemical reactions.
• 😀 Water hardness testing can be done simply by observing how much soap lathers when washing hands with the water sample.
• 😀 If the soap forms many bubbles, the water has low hardness. Fewer bubbles indicate higher hardness.
• 😀 The tools required for testing water hardness include a 10 mL pipette, funnel, 100 mL measuring flask, Erlenmeyer flask, burette, stirring rod, and specific chemical indicators.
• 😀 Use a water sample of 100 mL for the hardness test.
• 😀 The pH indicator and 50 grams of EDTA (ethylenediaminetetraacetic acid) are added to the water sample to prepare it for titration.
• 😀 Titration is performed by slowly adding EDTA solution until the color changes from dark red to ocean blue.
• 😀 It’s crucial to record the initial volume of the EDTA solution before starting the titration for accurate results.
• 😀 The formula for calculating water hardness involves multiplying the volume of EDTA used by a constant factor and dividing by the molar mass of calcium carbonate.
• 😀 The result of the titration, combined with the formula, gives the total hardness of the water in mg/L as CaCO₃.
• 😀 The final result helps determine whether the water sample is soft or hard based on the amount of EDTA solution required to neutralize its hardness.

Q & A

What is the main objective of the water hardness testing demonstration?

The main objective is to demonstrate how to test the hardness of water using a titration method with EDTA solution, and to understand the relationship between water hardness and soap foam formation.

Why is it important to use gloves and a mask during the testing process?

Gloves and a mask are used to protect the skin and respiratory system from potential chemical reactions and exposure to harmful substances during the testing procedure.

How does the amount of soap bubbles indicate water hardness?

When the water has low hardness, it produces more soap bubbles, indicating fewer minerals (like calcium and magnesium). High hardness results in fewer bubbles because the minerals in the water interfere with the soap's ability to form lather.

What are the main tools and chemicals used in the water hardness testing?

The main tools are a pipette, measuring cylinder, funnel, Erlenmeyer flask, buret, stirring rod, and spoon. The chemicals include pH indicator solution, EDTA solution, and the water sample to be tested.

What is the first step in the hardness testing procedure?

The first step is to measure 100 ml of the water sample using a 100 ml measuring cylinder and transfer it to an Erlenmeyer flask.

How do you prepare the water sample for titration?

The water sample is prepared by adding 25 ml of pH indicator solution, followed by 50 grams of EDTA. The solution is stirred until it turns dark red.

What is the significance of the color change from dark red to ocean blue during titration?

The color change from dark red to ocean blue indicates the endpoint of the titration, where all the calcium and magnesium ions in the water sample have reacted with the EDTA solution.

How do you calculate the total hardness of water from the titration results?

The total hardness is calculated using the formula: Total Hardness = (100 * PML * N_EDTA) / Factor * M_CaCO3, where PML is the volume of EDTA used, N_EDTA is the normality of the EDTA solution, and M_CaCO3 is the equivalent mass of CaCO3.

What does the PML value represent in the calculation?

PML represents the volume of EDTA solution used during the titration process, which is crucial for determining the total hardness of the water sample.

Why is EDTA used in the hardness testing process?

EDTA is used because it forms stable complexes with calcium and magnesium ions, which are the primary contributors to water hardness. The volume of EDTA required to bind these ions helps determine the hardness level.