Praktikum Kimia Dasar Modul 2. Stoikiometri

Summary

This video provides a step-by-step guide on conducting various stoichiometry experiments. It covers three main topics: determining the empirical formula of compounds, identifying the limiting reactant in a reaction, and analyzing volumetric titration. The video begins with instructions on weighing and preparing materials, followed by practical demonstrations such as burning magnesium, using a centrifuge to separate mixtures, and performing titration to determine the molarity of an unknown acid. Each experiment is explained clearly, and students are given tasks to calculate molecular ratios and reactant limitations.

Takeaways

• 📘 The video focuses on three practical experiments related to stoichiometry.
• 🔬 The first experiment is about determining the empirical formula of compounds through combination reactions.
• ⚖️ The empirical formula experiment involves heating a crucible with magnesium and measuring the mass change to calculate molar ratios.
• 🔥 Magnesium is burned under a bunsen burner, and the experiment checks the mass difference before and after the reaction.
• 📊 The second experiment focuses on limiting reactants and the precipitation of salts from a mixture of compounds.
• ⚗️ The reactants in the second experiment are a mixture of calcium chloride (CaCl2), potassium oxalate (K2C2O4), and water.
• 🔍 The experiment involves filtering the mixture, drying the sample, and determining the mass of calcium oxalate formed.
• 🧪 The final experiment involves volumetric analysis to determine the molarity of an unknown acid using NaOH titration.
• 📏 The titration process measures how much NaOH is needed to neutralize the acid, and the endpoint is determined with a phenolphthalein indicator.
• 🏁 The video concludes with tasks for the students to calculate empirical formulas, molar ratios, and molar concentrations based on their experiment results.

Q & A

What is the first experiment discussed in the video?

The first experiment discussed is the determination of empirical formulas, which involves determining the empirical formula of two compounds using a combination reaction.

What are the objectives of the empirical formula experiment?

The objectives of the empirical formula experiment are to determine the empirical formula of two compounds through combination reactions and to determine the molar ratio of the products formed from the decomposition of a compound.

What materials are used for the empirical formula experiment?

The materials used include crucibles (one with a lid and one without), a Bunsen burner connected to gas, and magnesium ribbon (Mg).

How is the mass of magnesium (Mg) determined before combustion?

The mass of the magnesium is determined by subtracting the initial weight of the empty crucible from the weight of the crucible with the magnesium ribbon inside.

What happens during the combustion of magnesium?

During the combustion of magnesium, the ribbon is heated using a Bunsen burner until it fully burns and stops producing flames. The process is monitored every 30 seconds, and the flame is extinguished when the burning stops.

What should be done after the magnesium has completely burned?

After the magnesium has completely burned, the crucible is cooled and placed in a desiccator before being weighed to calculate the mass change.

What is the second experiment in the video?

The second experiment is about determining the limiting reactant and the precipitation of salt from a reaction. This experiment involves a mixture of salts like CaCl2, H2O, and K2C2O4 in a specific ratio.

What is the purpose of the limiting reactant and precipitation experiment?

The purpose is to identify the limiting reactant in the mixture of salts and determine the percentage composition of each substance in the mixture.

How is the precipitate filtered and measured in the second experiment?

The precipitate is filtered using a filter paper, which is weighed before and after the process to determine the mass of the precipitate collected.

What is the final experiment in the video about?

The final experiment is about volumetric analysis, where the goal is to determine the molar concentration of a strong acid (HCl) by titrating it with a known concentration of NaOH (0.1 M).