Hydrogen Chloride Chemistry PDF, ICSE Class 10

.UE tr&ffi, TMnoRTANT TERMS, DEFINITIoNS AND REAcTIoNS 1. Hydrogen chloride gas was first prepared by Glauber in 1648. Humphrey Dary in 1810 proved th- r to be a compound of hydrogen and chlorrne. ) It 3. It or H8+ x H' + .Cl:-----+ is a polar covalent compound. Cl8- is synthesised from its...

.UE tr&ffi, TMnoRTANT TERMS, DEFINITIoNS AND REAcTIoNS 1. Hydrogen chloride gas was first prepared by Glauber in 1648. Humphrey Dary in 1810 proved th- r to be a compound of hydrogen and chlorrne. ) It 3. It or H8+ x H' + .Cl:-----+ is a polar covalent compound. Cl8- is synthesised from its elements in the presence of diffused sunlight. -ffi#- Hzk) + crzk) zHct(g) 4. Hydrogen chloride is prepared in laboratory by the reaction of sodium chloride with concenrah sulphuric acid (Fig. 1). €- Conc. sulphuric acid Dry HCI gas Conc. sulphric acid (i) (ll) Hydrogen chloride gas Fig. 1: Laboratory preparation of hydrogen chloride gas Reactants used for the preparation of hydrogen chloride gas are sodium chloride and conceiri ,:r sulphuric acid. sodium chloride is preferred over other metallic chlorides as it is easily ava--.! and cheaply. Condition of the reaction: The temperature should be maintained below 200 'C. (iii) NaCl + HrSOo(con..) Sodium -H+- + HClt NaHSOo Sodium Hydrogen bisulphate chloridegas chloride 2NaCl + HrSOo(conc.) -rrr.4!*- NarSoo + Sodium sulphate Sodium chloride IHCII Hydrogen chloride gas (iu) Procedure: Thke some sodium chloride (common salt) in a round bottom flask and set-rr I apparatus as shown in figure 1. Pour concentrated sulphuric acid. On heating the mixture e;:.: HCI gas is evolved. (u) Precautions observed during the laboratory preparation of hydrogen chioride gas: (a) The reaction mixture should not be heated beyond 200 "C as above 200 "C, a sticky mass sodium sulphate is formed which sticks to glass apparatus and is difficult to remove. (b) Fuel is wasted if heated above 200 "C and glass apparatus must crack. (vl) Collection: Before collection, hydrogen chloride gas is dried by passing through concentrau sulphuric acid. It is not dried by passing through phosphorous pentaoxide and calcium ol-= both of these drying agents undergo chemical reaction with hydrogen chioride gas. + 3HCl ---------+ POCI3 + 3HPO3 CaO + ZHCL -------+ CaCl, + H2O 2P2Os Dry hydrogen chloride gas is collected in by a gas jar upward displacement of air as the gas is heari than air and it is not collected over water as it is highly or extremely soluble in water. Therefc:=. forms hydrochloric acid. l,OE" Zr9"*., *a4@ Chemistry (ICSE)- 10 jar is filled with hydrogen chloride gas, bring a glass [wl) Identification: In order to know that the gas rod dipped in ammonium hydroxide near its mouth. If dense white fumes appear immediately, then it shows that the gas jar is filled with hydrogen chloride gas. Hydrogen chloride gas is dissolved in water with the help of special arrangement called funnel [ourg"ro"nt to prevent the back suction of water and gives greater surface area for the absorption bf the gas. Conc. sulphuric acid Fig. 2: Preparation of hydrochloric acid using funnel arrangement physicat properties of hydrogen chloride gas are: It is a colourless gas having pungent suffocating smell which gives dense fumes in moist air. It is highly or extremely soluble in water. Red fountain The extreme solubility of hydrogen chloridegascanbedemonstratedbyHffi-DryHClgas fountain experiment (Fig. 3). Fountain experiment: We take a dryround bottom flask filled with dry HCI and arrange the apparatus as shown in the figure. Fix a rubber stopper having two holes on the mouth of the flask. Pass jet tube through one hole and a containing a few drops of water another hole. Put the end of the jet containing waler a l",trJet tube -H- (dropper tl ---S----= through tl I ffi tube hl I H inabeakercontainingbluelitmussolution. [l ffiry re$---Brue.ritmus solution DroPPer I I When we press the dropper, we observe that blue litmus enters the jet tube with Fig. 3: Fountain experiment to demonstrate extreme solubility of a great fore and forms a red fountain. HCI gas This is because on pressing, the water from the dropper goes in the flask and HCl gas present in the flask get dissolved due to its high solubility in water, thereby lowering the inside pressure. The higher outside pressure pushes the blue litmus solution inside through the jet tube due to which it turns red as HCI gas is acidic in nature. (c) Hydrogen chloride gas is heavier than air. We take a jar with burning candle as shown in fig. 4. We take another jar full of HCI gas and pour it into the jar of burning candle. We observe that the candle extinguishes. It is because of jar and occupies the lower portion of the jar. _ HCI gas, being heavier, forces out the air in the 4 Hydrogen Chtoride ffi Fig.4 : Showing Hydrogen chloride gas is heavier than air Chemical properties 7. Hydrogen chloride gas is neither combustible nor it is a supporter of combustion. burning splinter. 8. Hydrogen chloride gas thermally decomporr"do *t" hydrogen and chlorine. It extingu l? 2HCl 9. Metals lying above -- Hz + Cl2 hydrogen in the metal activity series displace hydrogen when heated with h, chloride gas. - Mg+zHCl ^,MgClr+H, Zn -r zHCl ^ ' ZnCl, + H, Fe+2HCl ^'Feclz+H2 Ca+ZHCI ^'CaClr+H, 10. Hydrogen chloride gas reacts with ammonia to give dense white fumes of ammonium chlor::NH3 + HCI --------) NH4CI Dense white fumes 11. Hydrogen chloride gas is a polar covalent compound which on dissolving in water produces i,-,r 12. Hydrogen chloride gas on dissolving in water produces strong monobasic acid (hydrochloric ad HCIG)+H2O. -H3O++Cl- 13. Dry hydrogen chloride gas and liquified hydrogen chloride gas has no effect on litmus, shou.-; neutral (non-acidic) character of the dry gas. 14. Liquified hydrogen chloride gas does not allow the electric current to pass through it, shou,..: covalent nature of the gas. 15. In laboratory, Hydrochloric acid is prepared by dissolving hydrogen chloride gas in water. E: hydrogen chloride gas is directly absorbed in water, it leads to back suction. Therefore, the :r dissolved in Water with the help of funnel arrangement in order to prevent the back suction crt ';i which also provides maximum area for the absorption of hydrogen chloride gas. 16. Dilute hydrochloric acid is a typical acid. So, it undergoes the following reactions: (a) Reaction with indicator: Dilute solution of hydrochloric acid is strongly acidic and rt .: characteristic colours with indicators. Indicator Colour change Blue litmus Red Phenolphthalein Colourless Methyl orange Red or pink (D) Reaction with metallic oxides: On reaction with metallic oxides dilute Hydrochloric acid forms and water. tri;;:*"*rre," ffi *a4@ Chemistry "ae4i4& ICSE) - 10 r cuo+2HCl(dil.)cuclr+H2ONarO+2HCl(dil')---+2NaCl+HzO reaction to form bases, dilute HCI undergoes neutralisation Reaction with bases: On reaction with salt and water. NaOH + HCI (dil') -------+ NaCl Sodium + Sodium chloride hYdroxide KOH + HCl (dil') ---+ KCl + Sodium Potassium chloride hYdroxide H2O H2O a colourless acid reacts with active metals to liberate Reaction with metals: Dilute Hydrochl0ric a popping and odourless gas which burns with -- a sound' + H2t Mg + 2HCl (dil.) ---?Magnesium -rusclz Magneiium Fe + 2Hcl(dlt'; .-_' Iron Zr + ZHCI (dil.) ---+ Znc chloride Fecl' + H2t Ferrous chloride ZnClr+ H2t Znc chloride LAtcl\+ 3H2f 2A1 + 6HC1(dil.) Aluminium chloride Aluminium reacts with metallic bicarbonates: Dilute hydrochloric acid ' Reaction with metallic carbonates and lime water milky turns gas which odourless and colourless carbonates and bicarbonates to liberate dioxide' carbon is showing that the gas evolved 2HC1(di1') ------+ ]N3cr + H2o NarCo, * Sodium carbonate NaHCo, + HCI (dil.) ----) Sodium chloride * I?.Cl 'rO Sodium Sodium chloride bicarbonate Ca(oH), + CO2---) CaCOTJ + ttrO Lime water (clear solution of milk of lime) (f) Calcium carbonate * fgZt Carbon dioxide *.-tP:-- uaro9n dioxide t (milkY) Dilute hydrochloric acid reacts with metallic Reaction with metallic sulphites and bisulphites: sulphitesandbisulphitestoliberateacolourlessgashavinguurningsulphursmellwhichturns solution from to green and potassium permanganate acidified potassiuh dichromate from orange p,,p","i",""ffi ,ltJ;;;"1"HA,ffi T3,,XiUy"t;S"f:{d'r,.* sulphite NaHSO, + HCl (dil.) Sodiumbisulphite Sodium Sodium Potassium dichromate (orange) chloride + .!acl Sodiumchloride - HzO -^ sulPhate Sulphur dioxide I. lo't Sulphurdioxide sulPhate (Green) Hydrogen Chloride W il 2KMpOo + 5SO2 + 2H2O K2SO4+ 2MnSOo+ZH.SO Potassium sulphate -=+ Potassium permanganate Manganese sulphate (Purple) with metallic sulphides and bisulphides: Dilute hydrochloric acid reacts with met sulphides and metallic bisulphides to liberate a colourless gas having rotten egg smell which r lead acetate solution from colourless to shining black, showing that the gas evolved is hydrr Gr) Reaction sulphide. + Nars 2Hcl(dil.) 2NaCl + --------) Sodium chloride Sodium sulphide H2St Hydrogen sulphide (Rotten egg smell) NaHS HCI + NaCl ---------) + Pb(cH3coo)2 HrS + Sodium chloride (dil.) Sodium bisulphide ---------) Lead acetate PbS Lead (Colourless) H2St Hydrogen sulphide J + 2CH3COOH sulphide Acetic acid (BIack) (ft) Reaction with metallic nitrates: pb(No3)2 + 2Hcl(dil.) -------+ Lead nitrate + PbCl2J Lead chloride (White ppr.) 2HNO"J Nitric acid Lead chloride is a white precipitate which is soluble in hot water but insoluble in cold watt AgNO, + HCI(dil.) --------+ AgCIJ + HNO3 Silver nitrate AgCI Silver chloride (Curdy white ppt.) + 2NH4OH --------) [Ag(NH.)r]Cl + zHro Diammine silver(I) (l) Silver chloride is a curdy white precipitate which ,, ,:t;b1l in excess of ammonium hydrorr Reaction with thiosulphates: Dilute hydrochloric acid on reaction with sodium thiosulph produces sulphur dioxide and the solution formed has a yellow turbidity. NISzO: + zHCl --------) 2NaCl + HrO + SOz + - Sodium (dil.) thiosulphate Sodium chloride Sulphur S Sulphur dioxide (yellow resiclu. 17. Aqua regia is three parts of concentrated hydrochloric acid and one part of concentrated nitric It is used for dissolving noble metals like gold and platinum. HNO3 (conc.) Pt Au + 3HCl (conc.) -------) + + NOCI + zlctl + Nitrosyl Nascent chloride chlorine 4[Cl] --------+ PtCl4 (Platinum chloride) 3[Cl] --------+ AuCl, (Gold chloride) ,!!,,,.,rr,.,*. iffi Zry.rd", *a4@ Chemistry ICSE) - 10 2H)O ar (PbrOo), Concentrated hydrochloric acid is oxidised to chlorine by oxidising agents like red lead lead(IV) oxide (PbO 2),manganese(IV) oxide (MnOr), potassium dichromate (l{rCtrOz) and potassium permanganate (KMnOo). o 3Pbclz + Clz+ 4Hzo Pb3o4 + SHCI (conc.) o Pbclz+ Cl2+ zlH,zo Pboz + 4HCl (conc.) Mrrcl2 + Clz + zlH,zo trrtno, + +Hct (conc.) ' o'' '::f,",:"," o I{rCrro, + 14HCl (conc.) o 2KMno. + 16HCl (conc.) Tests for hydrogen chloride 2KCl + ZCrClr+ TIF.zo + 3C1z " zKCl + 2MnClz+ 5clz+ 8H2o ' gas: (a) It turns moist blue litmus paper red. (b) It gives dense white fumes with ammonium hydroxide' NH4OH + HCl t ---------) NH4CI + HzO Ammonium chloride (Dense white tumes) (c) It gives curdy white precipitate with silver nitrate solution, which is soluble in excess of ammonium (CurdY white PPt.) AgCl + 2NH4OH [Ag(NHr)r]Cl + z}{zo "'T#I;:'** (d) It gives a white precipitate with lead nitrate solution, which is soluble in hot water but insoluble in cold water. Pb(NO3)2 + zHCl -------) PbCl2J + 2HNO3 Lead chloride (White ppt.) Lead nitrate agents like manganese (IV) oxide, concentrated hydrochloric acid produces a greenish yellow coloured gas having pungent suffocating smell which turns: (e) On reaction with oxidising Mno, + 4HCl(conc.) --4- MnCl, + Cl, + zH2O Greenish Yellow gas ' (l) Moist blue litmus paper to red and finally bleaches it to white, i.e. decolourises Clz (il) HCI + HClo + }lzo------+ HClo ------+ HCI + [o] Moist starch iodide paper blue'black 2K1+ C[-zKCl + 12 20. Hydrochloric acid is extensively used in the manufacture of dyes, drugs, paints, and preparation of aqua-regia. tl. It is used in calico printing industry, tanning industry, etc' Hydrogen Chloride W