Chemistry Quiz 2

Historically, tannins extracted from oak galls were used for making ink by mixing them with iron compounds, such as iron(II) sulphate to form complex, water-soluble blue-black compounds.

Sodium is used in the yellow lamps used for street lighting. Sodium-vapour lamps are good for night-time illumination because of their high efficiency and because the light they produce penetrates mist and fog particularly well.

Oxygen is the most abundant element in the human body accounting for approximately 65% of a person's mass. Each water molecule consists of two hydrogen atoms bonded to one oxygen atom, but the mass of each oxygen atom is much higher than the combined mass of the hydrogen.

A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally pig iron. Blast furnace slag is a nonmetallic coproduct produced in the process. It consists primarily of silicates, aluminosilicates, and calcium-alumina-silicates.

In a lead-acid battery, the cathode is made of lead dioxide, and the anode is made of metallic lead. The two electrodes are separated by an electrolyte of sulfuric acid. Here, lead dioxide, lead metal, and sulfuric acid react to form lead sulphate and water; the separate processes are the oxidation of lead to lead sulphate at one electrode and the reduction of lead dioxide to lead sulphate at the other while the electric charge is transported through the electrolyte by the migration of hydrogen ions.

The major constituent of air is Nitrogen (N₂), which is about 78%. Oxygen (O₂) is the second most abundant gas at about 21%. The inert gas Argon (Ar) is the third most abundant gas at 0.93%.

Common alum (KAl(SO₄)₂·12H₂O) is added to water in order to destabilize the mud particles suspended in it. This process is known as coagulation. Alum helps in purifying water by aluminium which helps to coagulate the mud particles. Due to the high charge on aluminium ion (Al⁺³), it helps the small particles of suspended solids to group together until they are of such large size that they sink and can be removed.

Seawater can be purified by the process of distillation. Distillation is a phase separation method whereby saline water is heated to produce water vapor, which is then condensed to produce fresh water.

The polymerisation of ethylene is used in the manufacturing of polythene in industry. Polyethylene (also called polythene) is made through an addition polymerization reaction that utilizes an ethylene monomer (–C₂H₄–) repeated along the chain.

If there is no carbon dioxide (CO₂) in the earth's atmosphere, the temperature of the earth's surface would be less than the present. CO₂ is an important greenhouse gas that helps to trap heat in our atmosphere. Without it, our planet would be very cold.