CHAPTER NO 8

PHYSICAL PROPERTIES OF HYDROGEN AND USES OF HYDROGEN
PHYSICAL PROPERTIES OF HYDROGEN
At room temperature hydrogen is a gas.  It is a colorless, tasteless and odorless gas.  It is the lightest gas.  It is insoluble in water.  It is highly inflammable and burns with blue flame forming water.  Liquefication temperature of hydrogen is -252oC.  Bond energy of H-H is 431 Kj/mole.  Electro negativity of hydrogen is 2.1.  Ionization potential of hydrogen gas is 13.54 electron volt.
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USES OF HYDROGEN
It is used as a fuel.  It is used for the manufacturing of fertilizers.  It is used in the preparation of vegetable ghee.  It is used as rocket fuel.  It is used in the preparation of ammonia (NH3) and methanol (CH3OH).  It is used in the preparation of oxy-hydrogen flame which is used in welding due to production of high temperature.  It is used in filling weather balloons.  It is used to prepare tungsten filament.  It is used to prepare low temperature in liquid state.
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Question: Write the chemical formula of the following:
Baking soda: NaHCO3 (Sodium bicarbonate)  Washing soda: Na2CO3.10H2O (Hydrous sodium carbonate)  Caustic soda: NaOH (Sodium hydroxide)  Slaked lime: Ca(OH)2  Quick lime: CaO  Lime stone: CaCO3  Dolomite: CaCO3.MgCO3  Gypsum: CaSO4.2H2O  Epsomite (EPSOM SALT): MgSO4  Magnesite: MgCO3  Plaster of paris: CaSO4.1/2H2O Isotopes of Hydrogen   ISOTOPESNuclei of the same element having same atomic number but different mass number are known as isotopes. ORNuclei of same element having same number of proton but different number of neutron are knows as isotopes. Example 17Cl35 , 17Cl37 6C12 , 6C13 ISOTOPES OF HYDROGEN                          There are three isotopes of hydrogen. Protium Deuterium Tritium ProtiumOrdinary hydrogen is knows as protium . It has one electron ,one proton but it has no neutron. Mass number : 1 Charge number : 1 Symbol : 1H1 Percentage in natural hydrogen                    99.98% Structure Deuterium Heavy hydrogen is known as deuterium. It has one electron one proton and one neutron. Mass number: 2 Charge number: 1 Symbol: 1H2 or D Percentage In Natural Hydrogen0.0156% RatioProtium:Deuterium =1:15000Structure Heavy water(D2O) consists of deuterium isotope of hydrogen. TRITIUM It has one electron, one proton and two neutrons. Mass number : 3 Charge number : 1 Symbol : 1H3 Percentage in natural hydrogen4 X 10-15 % It is a radioactive isotope.                   It emits b-rays. It has a half life of 12.5 years. It is present in traces. Structure                            CHEMISTRY OF SODIUM CARBONATE ( Na2 CO3 )                                      INDUSTRIAL PREPARATION OF SODIUM CARBONATE   On industrial scale sodium carbonate is prepared by Ammonia Solvay Process. Raw Materials   1. Sodium Chloride 2. Lime Stone (CaCO3) 3. Ammonia Details of the process   At first stage a saturated solution of sodium chloride is prepared which is also known "BRINE". Composition of solution of NaCl (brine) is 28% m/m. Steps of preparation     Ammoniation of Brine   In this stage saturated brine is allowed to flow down an ammoniating tower. This tower is fitted with mushroom shaped baffles. These baffles control the flow of brine and ensure the proper mixing and saturation of ammonia. Carbonation of ammoniated brine   In the second step, ammoniated brine is allowed to trickle down a carbonating tower known as solvay tower. This tower is also fitted with baffle plates. Here brine is mixed with carbon dioxide gas, produced by heating lime stone in a separate chamber called "kiln". CaCO3 è CaO + CO2 the baffle plates ensure the flow of solution and breaks up carbon dioxide into small bubbles to produce good conditions for reaction. Flow Chart   Chemistry of Solvay tower   CO2 reacts with ammonia to form ammonium carbonate. 2NH3 + CO2 + H2O è (NH4)2CO3 Ammonium carbonate further reacts with CO2 to form ammonium bicarbonate. (NH4)2CO3 + CO2 + H2O è 2NH4HCO3 (aq.) Ammonium bicarbonate then react with NaCl to form sodium bicarbonate. NH4HCO3 + NaCl è NaHCO3 + NH4Cl Due to exothermic nature of above reactions, solubility of NaHCO3 increases. To counter this effect , lower part of Solvay tower is cooled , ppt of NaHCO3 are separated by vacuum filtration and washed to remove ammonium salts. Conversion of NaHCO3 to Na2 CO3   Dry sodium bicarbonate is heated in rotary furnace called "CALCINER" to give anhydrous sodium carbonate or soda ash. Carbon dioxide is re circulated to carbonation tower. 2NaHCO3 è Na2 CO3 + CO2 + H2 O Ammonia recovery process   When CaCO3 is heated, CaO is obtained along with CO2 . CaO is treated with water to form Ca(OH)2 . CaO + H2 O è Ca(OH)2 Quick lime is heated with NH4 Cl to form NH3 and calcium chloride (by product) . Ammonia is used again in this process. 2NH4 Cl + Ca(OH)2 è CaCl2 + 2NH3 + 2H2 O INDUSTRIAL PREPARATION OF SODIUM HYDROXIDE   SODIUM HYDROXIDE       Chemical formula : NaOH     Chemical name : sodium hydroxide     Commercial name : caustic soda RAW MATERIALS USED IN THE PREPARATION       Sodium chloride (NaCl).     Water (H2O).     PRINICIPLE       Sodium hydroxide is a strong base and is prepared by the electrolysis of aqueous solution of sodium     chloride known as brine. METHOD       PREPARATION OF BRINE:     NaCl is mixed in water to produce brine. Composition of brine is 25% m/m. ELECTROLYSIS OF BRINE       Electrolysis of brine is carried out in an electrolytic cell known as "Diaphragm cell". When an electric     current is passed through the brine, following changes take place.     Ionization of NaCl:           2NaCl ® 2Na+ + 2Cl-     Ionization H2O:               2H2O ® 2H+ + 2OH-     Electrochemical changes       At cathode:              2H+ + 2e- ® H2     At anode:                  2Cl- ®Cl2 + 2e-     During electrolysis, Na+ ions are not discharged but H+ ions are readily discharged. As more H+ ions     are discharged, more H2O dissociates to replace it. Na+ and OH- ions accumulate in the solution. On     evaporation sodium hydroxide is obtained.                                 Na+ + OH- ® NaOH WATER GAS-INDUSTRIAL PREPARATION OF HYDROGEN GAS WHAT IS WATER GAS?     A mixture of carbon monoxide and hydrogen gas is commonly known as water gas.                                                    [CO + H2] ® water gas     It is used as a fuel.     PREPARATION:     It is prepared by passing steam over red hot coke.                                                                         C + H2O ® CO + H2         WHAT IS WASHING SODA?     Sodium carbonate deca hydrated (Na2CO3.10H2O) is commonly known as washing soda.     WHAT IS BAKING SODA?     Sodium bicarbonate NaHCO3 is commonly known as baking soda.     WRITE DOWN INDUSTRIAL PREPARATION OF HYDROGEN GAS?     Hydrogen gas can be prepared by a lot of methods. Some important are as under.     BY THERMAL DECOMPOSITION OF METHANE:     When natural gas is heated up to 1000oC in the presence of catalyst, hydrogen gas is obtained.                                                     CH4 ®C + 2H2     BY COKE AND STEAM PROCESS:     When super heated is passed over red hot coke, a mixture of carbon monoxide and hydrogen is     obtained which is known as water gas.                                                   C + H2O ®CO + H2     By liquefication method pure hydrogen is separated.     BY THE ELECTROLYSIS OF WATER:     When pure water containing a little amount of H2SO4 or any ionic salt is electrolyzed, pure hydrogen is     obtained.     LANE’S METHOD:     When steam is passed over red hot iron, hydrogen gas is obtained.                                                3Fe + 4H2O ®Fe3O4 + 4H2     BY THE THERMAL DECOMPOSITION OF AMMONIA:     When ammonia gas is strongly heated it decomposes in to nitrogen and hydrogen.                                                2NH3 ® N2 + 3H2     N2 gas is separated by liquefication method. WHAT IS THERMITE PROCESS? THERMITE PROCESS: Reduction of metal oxides by aluminum is called thermite process. In this process a huge amount of heat is liberated which causes a temperature up to 3000oC. Due to this reason thermite process is used for welding of broken metal parts. 2Al + Fe2O3 ® Al2O3 + 2Fe + Heat  WHAT IS PLASTER OF PARIS? HOW IT IS PREPARED? WRITE ITS PROPERTIES?  CHEMICAL NAME: Calcium Sulphate Hemi Hydrated  CHEMICAL FORMULA: CaSO4.1/2H2O or (CaSO4)2.H2O COMMERCIAL NAME: Plaster Of Paris METHOD OF PREPARATION: When gypsum is heated to 100oC, it loses water molecules to produce plaster of Paris. 2(CaSO4.2H2O) ® (CaSO4)2.H2O + 3H2O PROPERTIES When plaster of Paris is ground to fine powder and mixed hard forming gypsum again. The setting results with expansion so the plaster of Paris fits tightly in to mold.