I/GCSE Chemistry Chapter Analysis - Chapter 2: Inorganic Chemistry - Acids, Bases and Salt Preparations (Part 2)

I/GCSE Chemistry Chapter Analysis - Chapter 2: Inorganic Chemistry - Acids, Bases and Salt Preparations (Part 2)

For I/GCSE Chemistry, you should know:

Now onto IGCSE Chemistry's Chapter 2: Inorganic Chemistry, focusing on the sub-topic of Acids, Bases, and Salt Preparations.

Bases: Metal Oxides, Metal Hydroxides, and Ammonia
In addition to the previous discussion, it's important to note that certain substances can also act as bases. These include metal oxides, metal hydroxides, and ammonia.

1. Metal Oxides as Bases:
   Metal oxides, such as sodium oxide (Na2O) and calcium oxide (CaO), can react with water to form basic solutions, producing hydroxide ions (OH-).
   Example: Na2O(s) + H2O(l) → 2NaOH(aq)
2. Metal Hydroxides as Bases:
   Metal hydroxides, such as sodium hydroxide (NaOH) and calcium hydroxide (Ca(OH)2), are strongly basic and readily dissociate in water to produce hydroxide ions (OH-).
   Example: NaOH(s) → Na+(aq) + OH-(aq)
3. Ammonia as a Base:
   Ammonia (NH3) is a colorless gas that can act as a base by accepting protons (H+) to form ammonium ions (NH4+).
   Example: NH3(g) + H2O(l) ⇌ NH4+(aq) + OH-(aq)

Alkalis are a specific type of base that are soluble in water, such as the metal hydroxides mentioned above. They produce hydroxide ions (OH-) when dissolved in water, making the solution basic.

Preparing a Pure, Dry Sample of a Soluble Salt
To prepare a pure, dry sample of a soluble salt, you can follow these general steps:

1. Prepare a solution of the acid and the alkali.
2. Mix the acid and alkali solution in the correct stoichiometric ratio to ensure complete neutralization.
3. Evaporate the water from the solution, leaving behind the salt.
4. Collect the dry salt and store it in a clean, dry container.

Example: Preparation of Sodium Chloride (NaCl)

1. Prepare a solution of hydrochloric acid (HCl) and a solution of sodium hydroxide (NaOH).
2. Mix the HCl and NaOH solutions in the correct ratio to completely neutralize the acid.
3. Evaporate the water from the solution, leaving behind the sodium chloride (NaCl) salt.
4. Collect the dry NaCl salt and store it in a clean, dry container.

Preparing a Pure, Dry Sample of an Insoluble Salt
To prepare a pure, dry sample of an insoluble salt, you can follow these general steps:

1. Prepare solutions of two soluble reactants that will form the desired insoluble salt.
2. Mix the two solutions, causing the insoluble salt to precipitate out.
3. Filter the precipitate to separate it from the remaining solution.
4. Wash the precipitate to remove any impurities.
5. Dry the precipitate to obtain the pure, dry sample of the insoluble salt.

Example: Preparation of Barium Sulfate (BaSO4)

1. Prepare a solution of barium chloride (BaCl2) and a solution of sodium sulfate (Na2SO4).
2. Mix the BaCl2 and Na2SO4 solutions, causing the insoluble barium sulfate (BaSO4) to precipitate out.
3. Filter the BaSO4 precipitate to separate it from the remaining solution.
4. Wash the BaSO4 precipitate to remove any impurities.
5. Dry the BaSO4 precipitate to obtain the pure, dry sample of barium sulfate.

By understanding the different types of bases, including metal oxides, metal hydroxides, and ammonia, as well as the procedures for preparing pure, dry samples of soluble and insoluble salts, you can effectively apply these concepts to various IGCSE Chemistry topics and laboratory experiments.

Work hard for your I/GCSE Chemistry examination!

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