Section 7: Phosphorus And Oxygen As Nonmetallic Elements

SECTION 7 : PHOSPHORUS AND OXYGEN AS NONMETALLIC ELEMENTS PHOSPHORUS The main source of phosphorus is phosphate rock known as apatite, Ca9(PO4 )6 .CaF6. There are several types of phosphorus, namely:    White phosphorus, with tetrahedral as its molecular shape, soft, very reactive and poisonous. This type of phosphorus is often referred to as yellow phosphorus because it is sometimes yellowish in color. Red phosphorus, the molecular form cannot be determined, is less reactive, and is not toxic. Black phosphorus (similar to graphite), obtained by heating white phosphorus under pressure at a temperature of 550 °C. Both red and black phosphorus are stable in air, but will burn if heated. Meanwhile, white phosphorus is easily ignited and very toxic, so it is stored in water.Phosphorus can be obtained from heating phosphate rock, silica (SiO2 ), and coke (C) in an electric burner. The phosphorus vapor formed is collected in water. Reaction: 2Ca3(PO4 )(s) + 6SiO2 (s) + 10C(s) P4(g) + 6CaSiO3 (l) + 10CO(g) The uses of phosphorus include:      Most phosphorus is used to produce phosphoric acid, where phosphorus acid is used in metal coatings to make it resistant to corrosion or can be used as a base layer in painting. Also used in the soft drink industry to provide flavorsour. Red phosphorus is used to make matches. Potassium phosphate is used as a food supplement and in baking soda. In the human body, phosphorus is found in nuclei, namely DNA and RNA and calcium phosphate as the main compound that makes up the bone matrix. Some phosphorus compounds are as follows. 1. Phosphoric Acid Pure phosphoric acid is a colorless crystalline solid, has a melting point of 42.35 °C. At low temperatures, phosphoric acid is very stable and does not have oxidizing properties, while at high temperatures it is quite reactive towards metals which reduce it.Phosphoric acid is obtained by reacting directly with phosphate rockwith concentrated sulfuric acid. Reaction: Ca3(PO4)2 (s) + 3H2SO4(aq) + 6H2O 3CaSO4 ·2H2O(s) + H3PO4(aq) If phosphoric acid is added to scoured apatite, it will be obtainedFertilizer with high phosphate content is called TSP (triple superphosphate).Apart from fertilizer, phosphoric acid is also used as a supporting materialdetergents, floor cleaning agents, insecticides, and pet food. 2. Superphosphate Fertilizer Phosphate salts are widely used in making fertilizer. Crushed phosphate rock can be used directly as fertilizer, but because of the solubility of Ca3(PO4) it produces "superphosphate" fertilizer.is very small, then 70% sulfuric acid must be added OXYGEN Oxygen is the most abundant element on earth and is the most important element in life. All living things need oxygen for the respiration process (breathing). Oxygen occurs in nature in the free state and in the form of compounds. In its free state in nature, oxygen has two allotropes, namely oxygen gas (O2) and ozone gas (O3). The abundance of oxygen in nature is ± 20% and in water ± 5%. The element oxygen easily reacts with all elements, except with light noble gases. Oxygen gas is colorless (solid/liquid oxygen/thick layer of light blue oxygen), odorless and tasteless so it is not detectable by our five senses.Oxygen condenses at –183 °C and freezes at –218.4 °C. Oxygen is an oxidizing agent that can oxidize metals and non-metals.Industrially, with the cryogenic separation process, air distillation will produce oxygen with a purity of 99.5%, while with the vacuum adsorption process, oxygen will be obtained with a purity of 90 – 93%. On a laboratory scale, oxygen can be obtained in the following way.     Heating a mixture of MnO2 and H2SO4 , this process was first introduced by CW Scheele (1771) Reaction: MnO2 (s) + H2SO4 (aq) MnSO4 (aq) + H2O(l) + O2 (g) HgO heating, this process was first introduced by Priesttley(1771) Reaction: 2 HgO(s) 2Hg(l) + O2 (g) Peroxide heating Reaction: 2BaO2 (s) 2BaO(s) + O2(g) Uses of oxygen include:     Oxygen gas is used for the breathing of all living things. Oxygen gas is needed for the combustion process. In the chemical industry, oxygen is used as an oxidizer to make chemical compounds. Liquid oxygen is used as rocket fuel.    A mixture of oxygen and hydrogen gas is used as fuelspacecraft (fuel cells). Together with acetylene it is used to weld steel. In the steel industry it is used to reduce internal carbon contentpig iron.