Praktikum Kimia Dasar: Stoikiometri Reaksi

Summary

This chemistry lab video outlines various experimental procedures, including the preparation and mixing of CuSO4 and NaOH solutions in different volumes for precipitation reactions. It also covers Pb acetate reactions, ammonia distribution between water and chloroform, and titration techniques using HCl. The script highlights key observations like the formation of precipitates, phase separation, and pH changes during titrations. The experiments focus on demonstrating chemical reactions, data collection, and qualitative analysis through visual indicators and measurements. The video concludes with instructions for further analysis and observations in each procedure.

Takeaways

• 😀 Prepare solutions of CuSO₄ (0.1 M) and NaOH (0.1 M) in different combinations for precipitation reactions.
• 😀 Shake the prepared mixtures and observe the formation of precipitates in different test tubes.
• 😀 Measure the height of the precipitates and record the data for each combination of solutions.
• 😀 For the Pb-acetate experiment, measure the mass of the empty test tube and then add Pb-acetate solution and KI to observe changes.
• 😀 Perform mass measurements after adding KI solution to record any mass changes due to reactions.
• 😀 In the ammonia distribution experiment, mix ammonium solution, water, and chloroform in an extraction flask.
• 😀 Shake the mixture and periodically open the tap to allow phases to separate. Observe and record the color changes during titration.
• 😀 Use methyl red as an indicator to observe pH changes during the titration with HCl (0.1 M).
• 😀 In the copper complex formation experiment, mix CuSO₄ (0.1 M) with ammonia (1 M) and shake the mixture.
• 😀 Perform phase separation and titration with HCl, observing the color changes in the aqueous phase.
• 😀 Record all observations, including the height of precipitates, color changes during titrations, and the volume of HCl used for titration.

Q & A

What is the first step in the precipitation reaction experiment?

The first step is to prepare a 0.1 molar CuSO4 solution (50 ml) and a 0.1 molar NaOH solution (1 ml), then mix them in a test tube and shake to combine.

How is the height of the precipitate measured in the experiment?

The height of the precipitate is measured using a ruler and recorded for each combination of solutions in the five test tubes.

What should be observed when mixing CuSO4 and NaOH solutions?

When the CuSO4 and NaOH solutions are mixed, a precipitate forms, which should be observed and recorded for each combination.

What is the purpose of using an analytical balance in the second procedure?

The analytical balance is used to measure the mass of the empty test tube and the mass after adding the Pb-acetate solution to ensure accurate measurements.

How is the mass change recorded in the second procedure?

The mass of the test tube is recorded first when empty, and then the mass is recorded after adding 2 ml of Pb-acetate solution, noting the changes during mixing.

What is the function of the methyl red indicator in the ammonia distribution experiment?

The methyl red indicator is used to detect changes in pH during the ammonia distribution, indicating whether the ammonia is in the aqueous or organic phase.

How is the separation of phases achieved in the ammonia distribution experiment?

The mixture is allowed to settle, and the two phases (water and chloroform) are separated, with the aqueous phase being analyzed after titration with HCl.

What is the next step after preparing the ammonia and chloroform mixture in the lab extraction flask?

After preparing the mixture in the lab extraction flask, it is shaken for approximately five minutes, with periodic opening of the tap to allow for proper phase separation.

What is observed during the titration in the ammonia distribution experiment?

During the titration, the color change of the aqueous phase (blue) is observed as it reacts with HCl, indicating the amount of ammonia present in the solution.

How does the reaction between CuSO4 and NaOH relate to the stoichiometry concept?

The reaction between CuSO4 and NaOH involves the precipitation of copper hydroxide, demonstrating stoichiometric principles by combining exact molar quantities of both solutions.