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Hydrogen chloride
It is colorless gas, its relative density according to air is 1.12601 at 0C0 it is appeared as smoke in the gases state it change to colorless liquid at(10C0 , 40 atom ) &(-83.7C0 , 1atom ) its mp is -112C0 dry hydrochloric acid dose not connect electricity but with moisture it connect electricity very well, at (S T P ) stander temperature and presser (t=25C0 , P=760mmHg) 503volume of hydrogen chloride dissolved in one volume of water exothermally the heat of hydration is (17.32Cal/mole) for one gram of, the hydrogen chloride dissolved in 100ml of water
Of one atmospheric the constant boiling point. Of mix contain 20.24% is 110 if the .concentration is more than 20.24% HCl will. volatized till the concentration become 20.24% and if the concentration is less than 20.24% water will volatized till the concentration become 20.24%
The affinity of chlorine to hydrogen
Chlorine can react with hydrogen with aflame and this flame is in absence of oxygen .this reaction is safe and easily demonstrated in absence of sun light , but presence of sun light this reaction will be more rabid and lead to explosion
H2 + Cl2 → 2HCl ∆H= -184 KJ/mol
This reaction can easily demonstrated by introducing a jet of burning hydrogen into gas jar full of chlorine .the formation hydrogen chloride is soon apparent, as misty fumes form at the mouth of the jar this flame occur with aflame
Chlorine gas also can react with hydrogen indirectly and this indicate the high affinity of chlorine to hydrogen, the affinity of this element to hydrogen by its ability to remove the hydrogen from any compound , this reaction is very important and can be easily demonstrated .
(a) When burning taper is lowered into a gas jar full of chlorine it continues to burn with reddish flame, producing a cloud of soot and gas which fumes in dump air. The fumes are identified if some ammonia is blown over the mouth
The taper is composed of hydrocarbon (compounds consisting of carbon and hydrogen only). Hydrogen chloride is the forming gas producing by combination of chlorine with hydrogen ,thus leaving carob in the in the form of soot , with ammonia the hydrogen chloride form dens white cloud of ammonium chloride.
This type of reaction can be over more strikingly illustrated by using some glass wool soaked in hoe turpentine (C10H16) in stead of burning taper
C10H16 +8Cl2 → 10C +16HCl
(b) When gas jar full of hydrogen sulphide and moist chlorine are mixed a pale yellow deposit of sulfer is formed and hydrogen chloride is again produced. Alternatively, chlorine may be bubbled through hydrogen sulphide solution
H2S (aq) + Cl2 (g) → 2HCl (aq) + S
(c) If few drops of concentrated ammonia solution are dropped from pipette into a gas jar full of chlorine, ammonia gas form the solution burns and white cloud of ammonium chloride are formed. This reaction occur in tow steps
2NH3+3Cl2→N2+6HCl
6NH3+6HCl→6NH4Cl
[8NH3+3Cl2→6NH¬4Cl+N2
8NH3 (g) +3Cl2(g) →6NH4Cl(s) +N2 (g)
Production of hydrogen chloride economically
Hydrogen chloride can be produced economically by four method
1-reaction between sodium chloride and sulfuric acid
2-as byproduct in the chlorination of the organic compounds
3-direct combination between hydrogen and chlorine
4-Hargreaves method
Production of hydrogen chloride economically by using reaction between sodium chloride and sulfuric acid
Sodium chloride is cheep and present in the earth crust by large amount so it is used in the production of HCl
NaCl +H2SO4→ NaHSO4 +HCl
The reaction is very rapid and highly exothermic so we decrease the surface area by using lumps salt or fused salt (let it to be melt then do solidification to aggregate the grinds of the salt) to decrease the rate of the reaction the device used in this method must be provided by cooling system the evaluated gas contain about 70:30% (volume ) hydrogen chloride others is salt vapor air and chlorine so the evaluated gas path through precipitating chamber then cooled to 40C0with cooling tubes and cooling tours then path through charcoal filter to purification it completely and remove sulfuric acid and small particles then it dissolved in water with cooling
Production of hydrogen chloride economically as byproduct in the chlorination of the organic compounds .
When chlorination to the organic compound hydrogen chloride is always formed
RCOOH + PCl5¬ → POCl3 + RCOCl +HCl
PhH + Cl2 → (AlCl3) → phCl + HCl
RCOOH + SOCl2 →RCOCl + SO2 +HCl
The evaluated gases are not mainly hydrogen chloride but it also has impurities of air & remains of organic compound. If the organic compounds have high boiling point it is separated by fractional condensation. But if it have low boiling point it is separated by solvent extraction using water as organic compounds do not dissolved in water however hydrogen chloride can be dissolved in water.
If we want anhydrous hydrogen chloride it can be added to condenser to do fractional distillation to separate other impurities.
Production of hydrogen chloride economically by using direct combination between hydrogen and chlorine.
It can be produced by the following device
1- chlorine come from the electric device path into cooling system then it is washed by H2O to dissolve impurities in water then water is heated to separate the chlorine (solubility of the gas decrease by heating) the evaluated chlorine is hydrated (80%) so it is added to drying unite (container which in the chlorine baths from down to up in opposite of continuous stream of sulfuric acid baths from up to down to establish the maximum combination between the sulfuric acid and chlorine ) then the dry chlorine baths through sand filter to extract all the impurities then it is bombed to the ignition furnace
2- Hydrogen is cooled in the cooling unite then is added to drying unite (container which it the hydrogen baths from down to up in opposite of continuous stream of sulfuric acid bathed from up to down to establish the maximum combination between the sulfuric acid and hydrogen) then it is bombed to the ignition furnace
3- In the furnace chlorine gas is react with the hydrogen gas exothermally to produce hydrogen chloride.
H2 (g) + cl2 (g) → HCl (g)
This reaction must be in dark not to lead to explosion.
The produced hydrogen chloride bathed through condensers and cooler of graphite then dissolved in water to produce 30% concentrated hydrogen chloride the remaining hydrogen chloride is dissolved in water in a tour lined with kawichowck which cooled and feed by water by closed cycle ( water go out from this tour it is cooled then inter it again to dissolve hydrochloric acid other (by cooling solubility increase)
The remaining hydrogen chloride is derived away by using very long chimney or washed by using NaOH sodium hydroxide thin derived away
Production of hydrogen chloride economically Hargreaves method
4NaCl + 2SO2 + O2 + 2H2O → 2Na2SO4 + 4HCl
It is better than reaction of sodium chloride with the sulfuric acid as one mole of sulfuric acid give one mole of hydro chloric acid and sodium bisulfate but one mole of sulfer dioxide gives tow moles of hydrogen chloride and sodium sulfate.
It is based on continuous stream of sulfer dioxide bathed through porous blocks of used salt (used before in this method) with water and air in vertical tour then bathed on porous blocks of new salt
The temperature change from 100C0 in the first chamber to 600C0 in the last one the produced gas is absorbed in water.
This method produce the largest amount of hydrogen chloride and also lead to escape the largest amount of it to atmosphere specially in the old reactors such as (Manheim reactor) which is not tightly closed and also and when exchange the hot blocks of salt.
In the new ovens escaping of the gas is controlled by using evacuated vanes which keep the presser of the reactor less than the presser of the atmosphere and also provided by cooling system for the hot blocks of the salt by moving it on strap before evacuate it so the escaping hydrogen chloride decrease by large amount
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