Kimia Dasar 2 : Kesetimbangan (Spektrofotometer UV-VIS)

Summary

This video covers a basic chemistry practical session focused on equilibrium reactions. The first experiment explores iron(III) equilibrium, where students observe changes in color upon mixing different substances, aiming to understand coordination bonding and equilibrium shifts. The second experiment uses a UV-Vis spectrophotometer to measure the absorbance of CuCl2 solutions at varying concentrations, guiding students in calculating unknown concentrations using linear regression. The session concludes with a reminder to calculate the concentration of CuCl2 samples, offering valuable hands-on experience in chemical analysis and equilibrium studies.

Takeaways

• 😀 The experiment focuses on studying equilibrium reactions and observing physical changes that occur during the reactions.
• 😀 One of the objectives is to measure physical parameters using assisting instruments during the experiment.
• 😀 The experiment includes studying equilibrium constants based on experimental data.
• 😀 The first experiment involves the equilibrium of iron (III) with SCN- and includes adding different substances to four test tubes.
• 😀 The four test tubes are treated with different reagents such as concentrated SCN, phenol, and Na2HPO4 to observe color changes.
• 😀 Students are asked to determine how the coordination bond between iron and SCN ions affects equilibrium.
• 😀 The second experiment involves measuring the concentration of CuCl2 solutions using a UV-Vis spectrophotometer.
• 😀 The spectrophotometer is used to measure absorbance or transmission of a solution at a specific wavelength.
• 😀 A blank solution (aquades) is measured first to calibrate the spectrophotometer.
• 😀 The absorbance of CuCl2 solutions with varying concentrations is measured, and a sample's concentration is determined using linear regression.
• 😀 The session concludes with a reminder for students to calculate sample concentrations and use linear regression for data analysis.

Q & A

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

The purpose of the first experiment is to study equilibrium reactions by observing physical changes and measuring physical parameters using supporting instruments. It also aims to study the equilibrium constant based on experimental data.

What is used in the first experiment to observe equilibrium reactions?

In the first experiment, a 0.002 M KSCN solution is used. This is combined with iron(III) chloride to observe changes and analyze the reaction between them.

What are the steps followed in the first experiment for observing changes?

First, the KSCN solution is measured and added to separate test tubes. Then, various substances, such as concentrated KSCN, phenolphthalein, and sodium phosphate, are added to each test tube. The color changes are observed, and the task is to determine how the equilibrium shifts based on these changes.

What does the second experiment in the script focus on?

The second experiment focuses on measuring the concentration of CuCl2 solution using a UV-Vis spectrophotometer.

What equipment is used in the second experiment for measuring absorbance?

The second experiment uses a UV-Vis spectrophotometer to measure the absorbance or transmittance of CuCl2 solutions at specific wavelengths.

How is the spectrophotometer set up for the second experiment?

The spectrophotometer is set to a wavelength of 510 nm, which is the absorption peak for CuCl2. A blank solution (distilled water) is first measured to set the instrument to zero absorbance.

What is the purpose of measuring a blank solution in the second experiment?

The blank solution (distilled water) is measured to calibrate the spectrophotometer, ensuring that the instrument reads zero absorbance before measuring the actual sample.

What concentrations of CuCl2 are tested in the second experiment?

Various concentrations of CuCl2, including a 0.02 M solution, are tested using the spectrophotometer to measure their absorbance values.

What task is assigned to the students in the second experiment?

Students are tasked with determining the concentration of a CuCl2 sample with an unknown concentration by using the absorbance data obtained from the spectrophotometer and applying linear regression.

How does the script conclude the laboratory session?

The script concludes by wrapping up the basic chemistry laboratory session, with the speaker expressing apologies for any errors and wishing the students success in their studies.