{"id":6065,"date":"2020-10-13T14:39:01","date_gmt":"2020-10-13T09:09:01","guid":{"rendered":"http:\/\/astan.lk\/al_virtualclassroom\/?p=6065"},"modified":"2020-10-13T14:39:57","modified_gmt":"2020-10-13T09:09:57","slug":"mineral-resources","status":"publish","type":"post","link":"https:\/\/astan.lk\/al_virtualclassroom\/mineral-resources\/","title":{"rendered":"s-block elements and their compounds"},"content":{"rendered":"

\u00a0Basic requirements for stabilising a chemical industry<\/h3>\n

\u2022 Capital \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u2022 Technology
\n\u2022 Availability of raw materials \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\u00a0 \u00a0 \u2022 Power (electricity, fuel, etc.)
\n\u2022 Labour \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u2022 Transport facilities and the market
\n\u2022 Waste management \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u2022 Controlling the environmental pollution
\n\u2022 Government rules and regulations
\n\u2022 Characteristics of natural resources that can be used as raw materials for an industry
\n\u2022 Occurring as large ores appropriate for long term usage
\n\u2022 Easy access \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u2022 High purity<\/p>\n

Occurrence of s-block elements and compounds<\/h3>\n

\u2022 s- block elements do not occur freely in the nature because they are very reactive and they exist as compounds<\/p>\n

Rock salt – NaCl
\nSea water – NaCl, MgCl2<\/sub>, CaCl2<\/sub>, CaSO4<\/sub>, Ca(HCO3<\/sub>)2<\/sub>, MgSO4<\/sub>
\nSilvine – KCl
\nBorax – Na2<\/sub>B4<\/sub>O7<\/sub>.10H2<\/sub>O
\nBeryl – 3BeO.Al2<\/sub>O3<\/sub>.6SiO2<\/sub>
\nMagnesite – MgCO3<\/sub>
\nDolomite – CaCO3<\/sub>.MgCO3<\/sub>
\nLimestone,Marble,Oyster shells – CaCO3<\/sub>
\nGypsum – CaSO4<\/sub>.2H2<\/sub>O
\nFluorspar – CaF2<\/sub>
\nApatite – Ca5<\/sub>(PO4<\/sub>)3<\/sub>X or 3Ca3<\/sub>(PO4<\/sub>)2<\/sub>.CaX2<\/sub> (X = F, Cl,OH)<\/p>\n

Extraction of Sodium (Down’s cell method)<\/h3>\n

\u2022 Sodium is extracted using electrolysis of molten NaCl. CaCl2<\/sub> is added to reduce the
\nmelting point of NaCl to 600 \u00b0C.
\n\u2022 At the cathode,
\nNa+<\/sup>(l) + e\u2192 Na(l)
\n\u2022 At the anode,
\n2Cl–<\/sup>(l) \u2192\u00a0Cl2<\/sub>(g) + 2e<\/p>\n

\u2022 Anode and cathode are separated by a circular disc (steel gauze diaphragm) to prevent the reaction between chlorine gas and sodium.<\/p>\n

\u2022 A large current is passed through the cell, but at a low voltage.<\/p>\n

\"\"<\/a><\/p>\n

Uses of sodium<\/h4>\n

\u2022 Sodium vapour lamps
\n\u2022 Molten sodium is used as a coolant in nuclear reactors.
\n\u2022 Solid sodium is used to dry organic solvents like ether and benzene.
\n\u2022 Used in organic synthesis
\n\u2022 Used to synthesise sodamide (NaNH2) which is a strong reducing agent.<\/p>\n

\u00a0Productionof s-block compounds<\/h3>\n

\u00a0Production of salt<\/h4>\n

The places where salt produced are referred to as saltterns. In Sri Lanka two main saltterns are placed in Puttalam and Hambantota.<\/p>\n

Characteristic features of the places where saltterns are established
\n\u2022 Plane land by the sea or lagoon \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u2022 Less rainfall
\n\u2022 Dry air, more sunlight \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u2022 Water impervious clay sand
\n\u2022 Sea water is used as the raw material.<\/p>\n

\"\"<\/a><\/p>\n

\u2022 Sea water is pumped into the first tank of the salttern. The sea water is evaporated by sunlight. When the concentration of sea water increases CaCO3<\/sub> gets precipitated in \u00a0the first tank of the salttern. CaCO3<\/sub> precipitate is allowed to settle down.<\/p>\n

\u2022 Remaining solution is transferred into the second tank of the salttern and evaporated by sunlight. When the concentration further increases CaSO4<\/sub> gets precipitated.<\/p>\n

\u2022 Remaining solution is transferred into the third tank of the salttern and evaporated. When the concentration further increases NaCl gets precipitated. NaCl is removed from the third tank of the salttern. This NaCl contains Ca2+<\/sup>, Mg2+<\/sup> and SO4<\/sub>2-<\/sup> as impurities.<\/p>\n

\u2022 Pure NaCl is not hygroscopic. But NaCl having the impurities is hygroscopic. Sodium chloride collected from the third tank is stored outside for nearly six months. During this storage period NaCl is almost purified as Ca2+<\/sup> and Mg2+<\/sup> salts absorb water from air and become solution while NaCl remains as a solid.<\/p>\n

\u2022 Iodized salt is produced by mixing with KIO3<\/sub>.<\/p>\n

\u00a0Uses of NaCl<\/h4>\n

\u2022 Cooking
\n\u2022 Food preservative (Maldivian fish, Pickle)
\n\u2022 Manufacture of Na metal, Na2CO3, NaHCO3 and NaOH
\n\u2022 Saline
\n\u2022 To reduce the melting point of ice
\n\u2022 As Mg2+ and Br- concentrations are high in bittern soultion it can be used to produce Mg and Br2.<\/p>\n

\u00a0Manufacture of Sodium Hydroxide<\/h3>\n

\u2022 Sodium hydroxide is commercially produced by the electrolysis of aqueous sodium chloride in chloro-alkali cells.<\/p>\n

\u2022 There are three types of chloro alkali cells
\n\u2022 Mercury cell \u2022 Diaphragm cell \u2022 Membrane cell<\/p>\n

\u2022 The membrane cell is very similar to the diaphragm cell and the same reactions occur. The main difference is that two electrodes of membrane cell are separated by an ion selective membrane rather than by a diaphragm.<\/p>\n

<\/p>\n

\u2022 The advantage of using membrane cell is that the NaOH that is produced is very pure and also uses less electricity, lowest environmental impact.<\/p>\n

\u2022 The half reactions are
\n2Cl–<\/sup>(aq) \u2192 Cl2<\/sub>(g) + 2e (at anode)
\n2H2<\/sub>O(l) + 2e \u2192 \u00a02OH–<\/sup>(aq) + H2<\/sub>(g) (at cathode)<\/p>\n

\u2022 The overal reaction is
\n2NaCl(aq) + 2H2<\/sub>O(l) \u2192 2NaOH(aq) + Cl2<\/sub>(g) + H2<\/sub>(g)<\/p>\n

\u2022 The anode is made of titanium and cathode is made of nickel.<\/p>\n

\u2022 The anodic and cathodic compartments are separated by a polymer cation-exchange membrane.
\n\u2022 The membrane can exchange cations and hence permits Na+ ions to migrate from anodic compartment to cathodic compartment.
\n\u2022 The flow of cations maintain electro-neutrality in the two compartments because, during electrolysis, charge is removed at the anode and supplied at the cathode.
\n\u2022 OH–<\/sup> would react with Cl2<\/sub>, and spoil the process. But migration of OH–<\/sup> is suppressed because the membrane does not exchange anions.<\/p>\n

\u2022 NaOH solution is partially evaporated and allowed to cool.
\n\u2022 Chlorine is produced as a by-product.<\/p>\n

Uses of sodium hydroxide<\/h4>\n

\u2022 Use in the laboratory as a convenient strong base
\n\u2022 Absorb carbon dioxide and other acidic gases
\n\u2022 Manufacture of soap, paper, atificial silk and dye stuffs
\n\u2022 Treatment of effluents for removal of heavy metals (as hydroxides) and of acidity<\/p>\n

\u00a0Uses of chlorine<\/h4>\n

\u2022 Used directly or in combination form as a bleach for textiles, wood, and paper pulps.
\n\u2022 Disinfection of drinking water
\n\u2022 One quarter of the hydrochloric acid produced in U.K. is synthesized from chlorine and hydrogen.
\n\u2022 Used in recovery of tin, titanium and magnesium from scrap.
\n\u2022 Used to produce chlorinated rubbers, insecticides, dyes and drugs.
\n\u2022 Used in the manufacture of polymeric materials such as polyvinyl chloride<\/p>\n

Manufacture of Soap<\/h3>\n

Oils, fats or their fatty acids and inorganic water soluble bases (NaOH, KOH) are used as raw materials.<\/p>\n

\u2022 The industrial soap making involves four basic steps.<\/p>\n

\u2022 Step 1 – Saponification
\nThe saponification process involves the mixing of tallow (animal fat), coconut oil or vegetable oil with sodium hydroxide and the application of heat. The process results in formation of soap, which is a salt of long chain carboxylic acid.<\/p>\n

<\/p>\n

 <\/p>\n

\u2022 Step 2 – Removal of glycerin
\nGlycerin is more valuable than soap, and hence most of it is removed for its uses in more expensive cosmetic products. Some of the glycerin is left in soap to make it soft and smooth.
\n\u2022 Step 3 – Soap purification
\nIn the soap purification stage any remaining sodium hydroxide is neutralized with a weak acid like citric acid and two thirds of the remaining water is removed to obtain pure soap.
\n\u2022 Step 4 – Finishing
\nThe final stage of industrial soap manufacturing process, finishing stage involves mixing of additives such as colours, preservatives and perfume into soap, which is then shapedinto bars for sale.<\/p>\n

\u2022 Instead of NaOH, KOH could be used. The soap manufactured using KOH is softer on skin. Therefore KOH is used mainly in the manufacture of baby soap.<\/p>\n

\u2022 The percentage of RCOO–<\/sup>Na+<\/sup> in the soap is referred as total fatty matter(TFM) value.<\/p>\n

Manufacture of sodium carbonate (Solvay Process)<\/h3>\n

\u2022 Brine (concentrated NaCl solution), limestone and ammonia (manufactured by Haber process) are used as raw materials.<\/p>\n

\u2022 NH3<\/sub> gas is dissolved in brine. This reaction is exothermic. Therefore low temperatures are favoured.<\/p>\n

\u2022 Counter current principle is used to achieve higher efficiency of dissolving.<\/p>\n

\u2022 Brine saturated with NH3<\/sub> is allowed to react with CO2<\/sub>(g) which is obtained by heating limestone. The reaction is exothermic. Therefore, low temperatures are favoured.<\/p>\n

\u2022 Again the counter current principle is used for achieving higher efficiency.<\/p>\n

Here, following reversible reactions take place.
\nNH3<\/sub>(aq) + H2<\/sub>O(l) \u2192 NH4<\/sub>+<\/sup> (aq) + OH–<\/sup>(aq)
\nOH–<\/sup> (aq) + CO2<\/sub> (aq) \u2192\u00a0HCO3<\/sub>–<\/sup>(aq)<\/p>\n

\u2022 As OH–<\/sup> is removed by the second reaction more and more OH–<\/sup> ions are formed by the first reaction.
\n\u2022 When HCO3<\/sub>–<\/sup> concentration increases NaHCO3<\/sub> crystallizes.
\nNa+<\/sup>(aq) + HCO3<\/sub>–<\/sup>(aq) \u2192 NaHCO3<\/sub>(s)
\n\u2022 Low temperature is maintained to facilitate the separation of solid NaHCO3<\/sub><\/p>\n

\u2022 NaHCO3<\/sub>(s) is isolated and heated. CO2<\/sub> formed is used again.
\n2NaHCO3<\/sub>(s) \u00a0\u2192\u0394<\/sup> \u00a0Na2<\/sub>CO3<\/sub>(s) + CO2<\/sub>(g) + H2<\/sub>O(g)<\/p>\n

\u2022 Net reaction for the formation of NaHCO3<\/sub> is
\nNaCl (aq) + NH3<\/sub>(aq) + CO2<\/sub>(aq) + H2<\/sub>O(l) \u2192 NaHCO3<\/sub>(s) + NH4<\/sub>Cl(aq)<\/p>\n

\u2022 The NH4<\/sub>Cl and lime are used to regenerate NH3<\/sub>. This NH3<\/sub> is used again.
\nCaO(s) + 2NH4<\/sub>Cl(aq) \u2192\u00a0CaCl2<\/sub>(aq) + 2NH3<\/sub>(aq) + H2<\/sub>O(l) or
\nCa(OH)2<\/sub>(s) + NH4<\/sub>Cl(aq) \u2192\u00a0CaCl2<\/sub>(aq) + NH3<\/sub>(aq) + H2<\/sub>O(l)<\/p>\n

<\/a><\/h4>\n

Uses of sodium carbonate<\/h4>\n

\u2022 Washing soda \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u2022 Manufacture of glass
\n\u2022 Softening of hard water \u00a0 \u00a0 \u00a0 \u2022 Manufacture of detergents
\n\u2022 Manufacture of soap \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\u2022 Manufacture of paper<\/p>\n

\u2022 The solubility of KHCO3<\/sub> is greater than that of NaHCO3<\/sub> and cannot be precipitated by the above method. Therefore, K2<\/sub>CO3<\/sub> could not be manufactured using Solvay process.<\/p>\n

\u00a0Manufacture of Quicklime (CaO)<\/h3>\n

\u2022 In this process alternate layers of crushed CaCO3<\/sub> and fuel (firewood) are fed into the kiln from top. A fire is started at the bottom and gradually spreads upward.<\/p>\n

\u2022 The high temperature causes CO2<\/sub> to be expelled from the kiln leaving CaO. After the kiln is cooled the quicklime is withdrawn from the bottom.<\/p>\n

\u00a0Disadvantages of this method<\/h4>\n

\u2022 Pollution due to the heat released to the environment.<\/p>\n

\u2022 Air pollution caused by CO2<\/sub> released and fine particles emitted.<\/p>\n

CaCO3<\/sub>(s) \"\"<\/a>\u00a0CaO(s) + CO2<\/sub>(g)
\nDissociation temperature of CaCO3<\/sub> (900 \u00b0C) is relatively high, if the fuel (firewood) does not supply this temperature CaCO3<\/sub> may not fully dissociate.<\/p>\n

\u2022 If CO2<\/sub> is not expelled fully from the kiln, it can combine with CaO again and form CaCO3<\/sub> (as the reaction is reversible).<\/p>\n

\u2022 CaO gets mixed with ash of the burnt fuel.<\/p>\n

 <\/p>\n

\u00a0Uses of CaO (Quicklime)<\/h4>\n

\u2022 Production of slaked lime and milk of lime
\n\u2022 Manufacture of calcium carbide
\n\u2022 Reducing acidity of the soil
\n\u2022 Manufacture of bleaching powder
\n\u2022 Construction of building
\n\u2022 Absorbing acidic gases<\/p>\n

\u00a0Manufacture of bleaching powder<\/h3>\n

\u2022 Heating limestone to obtain quicklime (CaO)
\n\u2022 Sprinkling water on CaO to obtain slaked lime [Ca(OH)2<\/sub>(s)] and allow to cool
\n\u2022 Passing Cl2<\/sub>(g) over wet solid Ca(OH)2 at room temperature for about 12-15 hours in rotating kilns with intermittent raking
\n\u2022 Counter current principle is used for higher efficiency of the reaction.
\nCaCO3<\/sub>(s) CaO(s) + CO2<\/sub>(g)
\nCaO(s) + H2<\/sub>O(l) \u2192\u00a0Ca(OH)2<\/sub>(s)
\n3Ca(OH)2<\/sub>(s) + 2Cl2<\/sub>(g) \u2192Ca(OCl)2<\/sub>.Ca(OH)2<\/sub>.CaCl2<\/sub>.2H2<\/sub>O(s)<\/p>\n

\u00a0Uses of bleaching powder<\/h4>\n

\u2022 Bleaching agent
\n\u2022 Disinfectant (especially for water)<\/p>\n

 <\/p>\n

Manufacture of calcium carbide (CaC2<\/sub>)<\/h3>\n

\u2022 Quicklime (CaO) and coke (C) are heated in an electric arc at a temperature of
\nabout 2000 \u00b0C.
\nCaO(s) + 3C(s) \u2192 \u00a0CaC2<\/sub>(s) + CO(g)
\n2CaO(s) + 5C(s) \u2192\u00a02CaC2<\/sub>(s) + CO2<\/sub>(g)<\/p>\n

\u2022 CaC2<\/sub> reacts with H2<\/sub>O and produces C2<\/sub>H2<\/sub>.
\nCaC2<\/sub>(s) + H2<\/sub>O(l) \u2192\u00a0Ca(OH)2<\/sub>(s) + C2<\/sub>H2<\/sub>(g)<\/p>\n

\u00a0Uses of CaC2<\/sub><\/h4>\n

\u2022 In the production of oxyacetylene flame
\n\u2022 Used to induce flowering
\n\u2022 Used to induce ripening of fruits<\/p>\n

 <\/p>\n

 <\/p>\n

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\u00a0Basic requirements for stabilising a chemical industry \u2022 Capital \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 […]<\/p>\n","protected":false},"author":842,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[14,1680],"tags":[],"class_list":["post-6065","post","type-post","status-publish","format-standard","hentry","category-chemistry","category-unit-15"],"acf":[],"yoast_head":"\ns-block elements and their compounds - Learning & Education Portal<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/astan.lk\/al_virtualclassroom\/mineral-resources\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"s-block elements and their compounds - 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