Kimia Dasar: Penetapan Kadar Karbonat dan Bikarbonat

Summary

This video script outlines a laboratory procedure for determining the concentration of carbonate and bicarbonate ions using titration with a standard 0.1 N hydrochloric acid solution. The process involves heating sodium carbonate, dissolving it in distilled water, and using indicators such as methyl orange and phenolphthalein to observe color changes during titration. The titration helps identify the endpoint, indicated by shifts in color from orange to red or colorless. The video also provides instructions for the preparation and measurement of the required solutions and equipment to complete the experiment successfully.

Takeaways

• 😀 The experiment involves determining the carbonate and bicarbonate content in a sample using titration with hydrochloric acid (0.1 N).
• 😀 Essential tools and materials include a beaker, Erlenmeyer flask, pipette, burette, methyl orange, phenolphthalein, sodium carbonate anhydrous, and hydrochloric acid.
• 😀 Sodium carbonate anhydrous is heated to a temperature of 260-270°C and then dissolved in 75 ml of distilled water (aquades).
• 😀 Methyl orange indicator is added to the sodium carbonate solution, causing the solution to change color to orange.
• 😀 The titration is performed using a 0.1 N HCl solution, during which the color changes from orange to red, indicating the end point for carbonate.
• 😀 The second titration involves using phenolphthalein as an indicator for bicarbonate determination.
• 😀 Phenolphthalein causes the solution to turn red when added to the bicarbonate sample, and the titration continues until the color changes to colorless.
• 😀 After the phenolphthalein step, methyl orange is added to the solution to finalize the titration for bicarbonate content.
• 😀 The required amount of hydrochloric acid used during both titrations indicates the quantity of carbonate and bicarbonate in the sample.
• 😀 The visual color changes observed during titration are key indicators for determining the completion of the titration process.

Q & A

What is the objective of the experiment described in the transcript?

The objective of the experiment is to determine the concentration of carbonate (CO₃²⁻) and bicarbonate (HCO₃⁻) in a sample using titration with a 0.1 N hydrochloric acid (HCl) solution.

What are the main materials used in this experiment?

The main materials include sodium carbonate anhydrous (Na₂CO₃), methyl orange indicator, phenolphthalein indicator, 0.1 N hydrochloric acid (HCl), and distilled water (aquades).

What equipment is required for the titration process?

The equipment needed includes a glass beaker, Erlenmeyer flask, Pasteur pipette, stirring rod, burette, and balance for weighing the chemicals.

How is the sodium carbonate solution prepared?

To prepare the sodium carbonate solution, weigh 0.2 grams of sodium carbonate anhydrous, dissolve it in 75 mL of distilled water, and add 2 drops of methyl orange indicator, which will turn the solution orange.

What is the purpose of adding methyl orange indicator to the sodium carbonate solution?

Methyl orange indicator is added to the sodium carbonate solution to help visually track the pH change during titration, indicating the transition from alkaline to acidic.

What color change indicates the endpoint during the first titration with HCl?

The endpoint of the first titration is indicated by the color change from orange to red when the sodium carbonate solution is neutralized by the hydrochloric acid.

How is the carbonate and bicarbonate sample titrated in the second part of the procedure?

For the carbonate and bicarbonate sample, 25 mL of the sample is titrated with 0.1 N HCl after adding 2 drops of phenolphthalein, which turns the solution pink. The titration continues until the solution turns colorless.

Why is phenolphthalein used in the second titration step?

Phenolphthalein is used to indicate the endpoint of the titration, as it turns from pink (alkaline) to colorless (acidic) when all the carbonate has been neutralized by the acid.

What happens after phenolphthalein is added and the titration reaches the endpoint?

After phenolphthalein is added and the titration reaches the endpoint, 2 drops of methyl orange are added. The solution turns orange, and titration with hydrochloric acid continues until the color changes from orange to reddish-orange, indicating the final endpoint.

How is the volume of hydrochloric acid used important in the experiment?

The volume of hydrochloric acid used during each titration is crucial for calculating the concentration of carbonate and bicarbonate in the sample, as it reflects how much acid was needed to neutralize the base.