Test for Calcium Radical

Theoretical Background / Context of Calcium Radical

• Calcium is a metallic element that occupies the 20th element in the periodic table. 
• It is located among group 2 metals that are called alkaline-earth metal. 
• Its chemical symbol is Ca. Calcium is the fifth most abundant element in both Earth’s crust and sea water by mass, where it represents around 3.4% of their mass. 
• Calcium has a silver metallic soft appearance.

Abundance of Calcium in Nature

Calcium is the fifth most abundant element in Earth’s crust, where it is not commonly found as a pure element. However, it is widely abundant as limestone (CACO3), quick lime (CaO), and calcium fluoride (CaF2).

Properties and Uses of Calcium

• Calcium is the lightest metal on Earth as its density is 1.55 gm/cm3. It was first isolated as pure calcium in the 1800s through the electrolysis process. 
• Calcium is an essential element in life. Calcium is one of the main constituents of aquatic organisms’ shells, eggshells, coral reefs, human bones, and cow milk.

Inorganic Analysis of Calcium Salts

• There are many calcium salts that are used for various purposes.
• For instance, calcium carbonate is the main constituent of limestone and chalk. Calcite is a fundamental constituent of marbles and pearls. 
• Calcium carbonate is also used as an antacid and as a dietary supplement for the treatment of calcium deficiency or osteoporosis. 
• Calcium nitrate is used as a fertilizer.

Preparation of Calcium Chloride

Calcium chloride can be prepared through the reaction of calcium hydroxide and hydrochloric acid as shown below:

 Ca(OH)2 + HCl → CaCl2 + H2O

Properties and Uses of Calcium Chloride

• Calcium chloride is a white crystalline salt that is highly soluble in water producing colorless aqueous solutions.
• Calcium chloride has the chemical formula of CaCl2 with a molecular weight of 110.984 gm/mol.
• Calcium chloride salt possesses a melting point and boiling point of 782 ⁰C and 1600 ⁰C, respectively.
• Calcium chloride is commonly hydrated possessing a general formula of CaCl2.xH2O, where x is the number of water molecules.
• Since calcium chloride is highly hygroscopic in its anhydrous form, it is used as a desiccant.

Principle of Work

• In this test for calcium chemistry experiment, calcium ion in calcium chloride is detected through some identification and confirmatory tests. 
• The calcium radical is among the fifth group of basic radicals.
• During the calcium radical experiment, salt solubility in water will be tested. 
• Then confirmatory tests will be carried out which are ammonium carbonate test, calcium sulfate, potassium chromate, and flame test.

First:  Physical Appearance Test 

In this test, the physical appearance of calcium salt is investigated in terms of color, odor, texture, etc.

Second: Solubility Test 

In this test, a sample of the calcium chloride salt is tested for its solubility in cold and hot water if needed.

Third: Ammonium Carbonate Test

It depends on the fact that ammonium carbonate will react with calcium chloride forming calcium carbonate as a white precipitate that crystallizes upon boiling.  

Fourth: Calcium Sulfate Test - Confirmatory test for calcium radical

It depends on the fact that no precipitate will be formed as no reaction will be accomplished which confirms that the tested sample is calcium salt.

Fifth: Potassium Chromate Test 

It depends on the fact that no precipitate will be formed as no reaction will be accomplished which confirms that the tested sample is calcium salt.

Sixth: Flame Test 

It is also called a dry test as it uses the calcium chloride salt as it is without dissolving it in water. It depends on the fact that calcium chloride can change the non-luminous benzene flame into an ignited yellowish red colored flame.