Pembuatan dan Reaksi Logam Alkali | Kimia SMA | Tetty Afianti

Summary

This chemistry lesson explains the production and reactions of alkali metals, focusing on lithium, sodium, potassium, rubidium, and cesium. The production methods involve electrolytic processes, where each metal is extracted from its respective salts under high temperatures. The lesson also covers the chemical reactions of alkali metals with hydrogen, oxygen, halogens, and water, highlighting their vigorous reactivity. The video concludes with practice exercises, encouraging students to explain concepts such as the role of potassium chloride in lithium production and to write and name chemical reactions, providing a comprehensive overview of alkali metal chemistry.

Takeaways

• 😀 The lesson begins with a greeting and emphasizes the importance of reciting 'Bismillahirrahmanirrahim' for ease in understanding the material.
• 😀 The script discusses the production of alkali metals, starting with lithium (Li), which is extracted from the mineral spodumene and goes through several chemical processes including reactions with sulfuric acid and sodium carbonate.
• 😀 The process of electrolysis is key in obtaining lithium metal from lithium chloride, requiring high temperatures and energy costs, which can be reduced by adding potassium chloride.
• 😀 Sodium (Na) is produced using a method called the Sheldon process, where sodium chloride (NaCl) is electrolyzed with calcium chloride (CaCl2) to lower the melting point.
• 😀 Potassium (K) is primarily obtained from the mineral sylvite (KCl), and is produced by reducing molten potassium chloride.
• 😀 Rubidium (Rb) is produced by reacting sodium (Na) with rubidium chloride (RbCl) in a system where the equilibrium is shifted to produce rubidium gas.
• 😀 Cesium (Cs) is extracted from pollucite ore, with further reactions involving hydrogen sulfide and sodium chloride to obtain cesium metal.
• 😀 Alkali metals react with hydrogen gas (H2) to form alkali hydrides, such as sodium hydride (NaH) and lithium hydride (LiH).
• 😀 Alkali metals also react with oxygen to form oxides, peroxides, or superoxides depending on the metal and oxygen quantity.
• 😀 A common reaction involves alkali metals reacting with halogens to form salts, such as sodium chloride (NaCl) from sodium and chlorine.
• 😀 The alkali metals react vigorously with water to produce hydroxides and hydrogen gas, with potassium, rubidium, and cesium exhibiting particularly violent reactions.
• 😀 The lesson concludes with practice questions on the production and reactions of alkali metals, offering further learning opportunities.

Q & A

What is the source mineral of lithium used in its extraction process?

The source mineral of lithium is spodumene, which is heated with sulfuric acid to produce lithium sulfate, which is further processed to obtain lithium.

Why is potassium chloride (KCl) added during the lithium extraction process?

Potassium chloride is added to lower the melting point of lithium chloride during electrolysis, making the process more energy-efficient and reducing production costs.

How is sodium metal (Na) produced?

Sodium is produced through the electrolysis of molten sodium chloride (NaCl), which is mixed with calcium chloride (CaCl2) to lower the melting point and speed up the process.

What is the purpose of adding calcium chloride to sodium chloride during sodium production?

Calcium chloride is added to sodium chloride to lower the melting point of the mixture, which reduces energy requirements and accelerates the electrolysis process.

What happens during the electrolysis of sodium chloride?

During the electrolysis of sodium chloride, sodium metal is deposited at the cathode, while chlorine gas is released at the anode.

What is the primary source mineral for potassium, and how is potassium obtained?

The primary source mineral for potassium is sylvite (KCl). Potassium is obtained by reducing molten potassium chloride, which leads to the formation of potassium gas.

What is the key feature of the production process of rubidium (Rb) compared to other alkali metals?

Rubidium is produced by reacting sodium metal with rubidium chloride (RbCl), and the rubidium vapor is separated from the system to drive the reaction forward.

How is cesium (Cs) extracted, and what is its main source mineral?

Cesium is extracted from the mineral pollucite. The cesium is first reacted with hydrochloric acid and then further processed to obtain the metal form.

What types of compounds do alkali metals form when they react with oxygen?

When alkali metals react with oxygen, they form oxides. If oxygen is in excess, alkali metals form peroxides or superoxides, depending on the specific metal.

What is the general reaction when alkali metals react with halogens?

Alkali metals react with halogens (such as chlorine, bromine) to form ionic halide salts, such as sodium chloride (NaCl) or potassium bromide (KBr).

What happens when alkali metals react with water?

Alkali metals react vigorously with water, producing an alkali hydroxide (e.g., sodium hydroxide, NaOH) and hydrogen gas (H2). The reaction can be violent, especially with potassium, rubidium, and cesium.

Why is the reaction between alkali metals and water so vigorous?

The reaction between alkali metals and water is vigorous because alkali metals have low ionization energies, allowing them to react rapidly with water, producing heat, hydrogen gas, and an alkali hydroxide.

What is the primary function of electrolysis in the production of alkali metals?

Electrolysis is used in the production of alkali metals by using an electric current to break down molten salts (e.g., sodium chloride, lithium chloride) into their component elements, with the metal being deposited at the cathode and other substances (like chlorine gas) being released at the anode.