molar mass Avogadro Constant Mass of particle (in gram) Mole of particles Number of particles molar mass Avogadro Constant molar volume molar volume

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1 Short Notes: Form 4 Chemistry Chemical Formulae and Equation Calculation For Solid, liquid or gas number of mole = mass of subtance molar mass For gas (only) volume of gas number of mole = molar volme Molar mass = RAM/RMM/RFM in gram For Solution Molar volume = 24dm 3 at room temperature Molar volume = 22.4dm 3 at s.t.p. For quantity of particle(atom,molecule,ion) MV number of mole = 1000 M = molarity V = Volume of solution in cm 3 number of mole = quantity of particle Summary molar mass Avogadro Constant Mass of particle (in gram) Mole of particles Number of particles molar mass Avogadro Constant molar volume molar volume Volume of Gas 1

2 Chemical Formula Cation (Positive Ions) Ion Symbol Ion Symbol Ion Symbol Potassium K + Calcium Ca 2+ Aluminium Al 3+ Sodium Na + Magnesium Mg 2+ Iron (III) Fe 3+ Lithium Li + Zinc Zn 2+ Chromium(III) Cr 3+ Hydrogen H + Barium Ba 2+ Argentums(I) Ag + Iron (II) Fe 2+ Mercury(I) Hg + Tin (II) Sn 2+ Ammonium NH 4 + Lead(II) Pb 2+ Copper(II) Cu 2+ Manganese(II) Mn 2+ Anion (Negative Ions) Ion Symbol Ion Symbol Ion Symbol Oxide O 2 Hydroxide OH Ethanoate CH 3 COO Fluoride F Sulphate 2 SO 4 Manganate(VII) MnO 4 Chloride Cl Nitrate NO 3 Dichromate(VI) 2 Cr 2 O 7 Bromide Br Carbonate 2 CO 3 Phosphate 3 PO 4 Iodide I Thiosulphate 2 S 2 O 3 Formulae for Certain Molecule Karbon monoxide CO Ammonia NH 3 Carbon dioxide CO 2 water H 2 O Nitrogen monoxide NO Hydrogen chloride HCl Nitrogen dioxide NO 2 Tetrachloromethane CCl 4 Sulphur dioxide SO 2 Glucose C 6 H 12 O 6 Sulphur trioxide SO 3 Hydrogen bromide HBr Fluorine F 2 Hydrogen iodide HI Bromine Br 2 Hydrogen sulphide H 2 S Chlorine Cl 2 Ethanol C 2 H 5 OH Iodine I 2 Ethanoic Acid CH 3 COOH 2

3 Reaction of Group 1 Elements Periodic Table 1. Reaction with Oxygen The entire group 1 metal can react with oxygen to form metal oxide. 4Li + O 2 2Li 2 O 4Na + O 2 2Na 2 O 4K + O 2 2K 2 O The metal oxide of group 1 elements can dissolve in water to form alkali (hydroxide) solution Li 2 O + H 2 O 2LiOH Na 2 O + H 2 O 2NaOH K 2 O + H 2 O 2KOH 2. Reaction with halogen (Chlorine) 2Li + Cl 2 2LiCl 2Na + Cl 2 2NaCl 2K + Cl 2 2KCl 3. Reaction with water The entire group 1 metal can react with water to produce alkali (hydroxide) solution and hydrogen gas. 2Li + 2H 2 O 2LiOH + H 2 2Na + 2H 2 O 2NaOH + H 2 2K + 2H 2 O 2KOH + H 2 Reaction of Group 17 Elements 1. React with water Cl 2 + H 2 O HCl + HOCl Br 2 + H 2 O HBr + HOBr I 2 + H 2 O HI + HOI 2. React with Sodium Hydroxide Cl 2 + 2NaOH NaCl + NaOCl + H 2 O Br 2 + 2NaOH NaBr + NaOBr + H 2 O I 2 + 2NaOH NaI + NaOI + H 2 O 3. React with Iron 3Cl 2 + 2Fe 2FeCl 3 3Br 2 + 2Fe 2FeBr 3 3I 2 + 2Fe 2FeI 3 Preparation of Chlorine Gas 2KMnO HCl 2KCl + 2MnCl 2 + 5Cl 2 + 8H 2 O 3

4 Electrochemistry Electrolyte Ionisation of Electrolyte Ionisation of Molten Compound PbBr 2 Pb 2+ + Br NaCl Na + + Cl Al 2 O 3 2Al O 2 Ionisation of Aqueous Solution NaCl Na + + Cl HCl H + + Cl CuSO 4 Cu SO 4 H 2 O H + + OH H 2 O H + + OH H 2 O H + + OH Discharge of Positive Ion Na + + e Na Grey deposit is formed. Al e Al Grey deposit is formed. Pb e Pb Grey deposit is formed. Cu e Cu Brown deposit is formed. Ag + + e Ag Silver deposit is formed. 2H + + 2e H 2 Gas bubble is formed. A pop sound is produced when a lighted splinter is placed near the mouth of the test tube. Discharge of Negative Ion 2Cl Cl 2 + 2e Bubbles of pungent yellowish green gas are The gas turns moist litmus paper to red and then bleaches it. 2Br Br 2 + 2e Molten electrolyte: Brown colour gas is Aqueous solution: Light brown solution is formed. 2I I 2 + 2e Molten electrolyte: Brown colour gas is Aqueous solution: Light brown solution is formed. The solution turns blue when a few drops of starch solution is added in. 4OH O 2 + 2H 2 O + 4e Gas bubble is formed. Gas produces light up a wooden splinter. 4

5 Ionisation of Acid Acid and Base Hydrochloric Acid HCl H + + Cl HCl + H 2 O H 3 O + + Cl Nitric Acid HNO 3 H + + NO 3 HNO 3 + H 2 O H 3 O + + NO 3 Sulphuric Acid H 2 SO 4 H + + SO 4 2 H 2 SO 4 + 2H 2 O 2H 3 O + + SO 4 2 Ethanoic Acid CH 3 COOH H + + CH 3 COO CH 3 COOH + H 2 O H 3 O + + CH 3 COO Chemical Properties of Acid Acid + Reactive Metal Salt + H 2 Example: 2HCl + Zn ZnCl 2 + H 2 6HNO 3 + 2Fe 2Fe(NO 3 ) 3 + 3H 2 H 2 SO 4 + Pb PbSO 4 + H 2 6CH 3 COOH + 2Al 2Al(CH 3 COO) 3 + 3H 2 Acid + Metal Oxide Salt + H 2 O Example: 2HCl + ZnO ZnCl 2 + H 2 O 2HNO 3 + MgO Mg(NO 3 ) 2 + H 2 O H 2 SO 4 + CuO CuSO 4 + H 2 O 2CH 3 COOH + Na 2 O 2CH 3 COO Na + + H 2 O Acid + Metal Hydroxide Salt + H 2 O Example: 2HCl + Ca(OH) 2 CaCl 2 + 2H 2 O HNO 3 + NaOH NaNO 3 + H 2 O H 2 SO 4 + 2NH 4 OH (NH 4 ) 2 SO 4 + 2H 2 O or H 2 SO 4 + 2NH 3 (NH 4 ) 2 SO 4 CH 3 COOH + KOH CH 3 COO K + + H 2 O Acid + Metal Carbonate Salt + CO 2 + H 2 O Example: 2HCl + ZnCO 3 ZnCl 2 + CO 2 + H 2 O 2HNO 3 + CaCO 3 Ca(NO 3 ) 2 + CO 2 + H 2 O H 2 SO 4 + Na 2 CO 3 Na 2 SO 4 + CO 2 + H 2 O 2CH 3 COOH + MgCO 3 Mg(CH 3 COO) 2 + CO 2 + H 2 O 5

6 Solubility of Salt Salt Salt Solubility Salt of potassium, sodium and ammonium All are soluble in water Salt of nitrate All are soluble in water Salt of sulphate Mostly soluble in water except: (Pb) Lead sulphate (Ba) Barium sulphate (Ca) Calcium sulphate Salt of chloride Mostly soluble in water except: (Pb) Lead chloride (Ag) silver chloride (Hg) mercury chloride Salt of carbonate Mostly insoluble in water except: Potassium carbonate Sodium carbonate Ammonium carbonate Oxide and Hydroxide Solubility Oxide Mostly insoluble in water except: K 2 O and Na 2 O. Hydroxide Mostly insoluble in water except: NH 4 OH, KOH and NaOH Preparation of Salt Preparation of Soluble Salt Salt of Potassium, Sodium and Ammonium Acid + Alkali Salt + Water Example: Preparation of Sodium Chloride (NaCl) HCl + NaOH NaCl + H 2 O Salt of nonpotassium, Sodium and Ammonium Acid + Reactive metal Salt + Hydrogen Gas Acid + Metal Oxide Salt + Water Acid + Metal Carbonate Salt + Water + Carbon Dioxide Example: Preparation of Zinc Sulphate (ZnSO 4 ) H 2 SO 4 + Zn ZnSO 4 + H 2 H 2 SO 4 + ZnO ZnSO 4 + H 2 O H 2 SO 4 + ZnCO 3 ZnSO 4 + H 2 O + CO 2 6

7 Preparation of Insoluble Salt Ionic Precipitation Insoluble salts can be made by double decomposition. This involves mixing a solution that contains its positive ions with another solution that contains its negative ions. Example: Preparation of Silver Nitrate AgNO 3 (aq) + NaCl (aq) AgCl (s) + NaNO 3 (aq) Ag + (aq) + C1 (aq) AgCl (s) (ionic equation) Colour of Salt Salt or metal oxide Solid Aqueous solution Salt of: Sodium, Calcium, Magnesium, Aluminium, zinc, Lead, ammonium Colourless Chloride, sulphate, nitrate, carbonate Salt of Copper(II). Copper(II) Carbonate Green Insoluble Copper(II) sulphate, Copper(II) nitrate, Copper(II) chloride Blue Blue Copper(II) oxide Black Insoluble Salt of Iron (II) Iron(II) sulphate; Iron(II) nitrate; Iron(ID chloride Green Green Salt of Iron (III). Iron(III) sulphate; Iron(III) nitrate; Iron(III) Brown Brown chloride Lead Iodide Yellow Insoluble Lead Chloride Insoluble Zink oxide Yellow when it is hot and white when it is cold. Insoluble Lead(II) oxide Brown when it is hot and yellow when it is cold. Insoluble Magnesium oxide, Aluminium oxide Insoluble Potassium oxide, Sodium oxide, Calcium oxide Colourless 7

8 Heating effect on Salt Heating Effect CO 3 2 NO 3 SO 4 2 Cl Most Probably Release CO 2 Most Probably Release NO 2 Heating Effect on Carbonate Salt Carbonate Salt Equation of The Reaction Potassium carbonate Sodium carbonate Calcium carbonate Magnesium carbonate Aluminium carbonate Zinc carbonate Iron (III) carbonate Lead(II) carbonate Copper(II) carbonate Most Probably Release SO 3 CaCO 3 CaO + CO 2 MgCO 3 MgO + CO 2 Al 2 (CO 3 ) 3 Al 2 O 3 + 3CO 2 ZnCO 3 ZnO + CO 2 Fe 2 (CO 3 ) 3 Fe 2 O 3 + 3CO 2 PbCO 3 PbO + CO 2 CuCO 3 CuO + CO 2 Not decomposible Most Probably No effect Mercury(II) carbonate Silver(I) carbonate Ammonium carbonate 2HgCO 3 2Hg + 2CO 2 + O 2 2Ag 2 CO 3 4Ag + 2CO 2 + O 2 (NH 4 ) 2 CO 3 NH 3 + CO 2 + H 2 O Heating Effect on Nitrate Salt Nitrate Salt Equation of The Reaction Potassium nitrate Sodium nitrate Calcium nitrate Magnesium nitrate Aluminium nitrate Zink nitrate Iron (III) nitrate Lead(II) nitrate Copper(II) nitrate Mercury(II) nitrate Silver(I) nitrate Ammonium nitrate 2KNO 3 2KNO 2 + O 2 2NaNO 3 2NaNO 2 + O 2 2Ca(NO 3 ) 2 2CaO + 4NO 2 + O 2 Mg(NO 3 ) 2 2MgO + 4NO 2 + O 2 4Al(NO 3 ) 3 2Al 2 O NO 2 + 3O 2 Zn(NO 3 ) 2 2ZnO + 4NO 2 + O 2 4Fe(NO 3 ) 3 2Fe 2 O NO 2 + 3O 2 Pb(NO 3 ) 2 2PbO + 4NO 2 + O 2 Cu(NO 3 ) 2 2CuO + 4NO 2 + O 2 Hg(NO 3 ) 2 Hg + 2NO 2 + O 2 2AgNO 3 2Ag + 2NO 2 + O 2 NH 4 NO 3 N 2 O + 2H 2 O [NOTES: Nitrogen dioxide, NO 2 is acidic gas and is brown in colour.] 8

9 Heating effect on sulphate salt Most sulphate salts do not decompose by heat. Only certain sulphate salts are decomposed by heat when heated strongly. Zinc sulphate, Copper (II) sulphate, Iron (III) sulphate ZnSO 4 ZnO + SO 3 CuSO 4 CuO + SO 3 2Fe 2 (SO 4 ) 3 Fe 2 O 3 + SO 2 + SO 3 The heating effect on chloride salts All chloride salts are not decomposable by heat except ammonium chloride. Example: NH 4 Cl NH 3 + HCl Ammonium sulphate (NH 4 ) 2 SO 4 2NH 3 + H 2 SO 4 Identification of Gases Gasses Characteristics Oxygen Rekindle glowing splinter. Hydrogen Explode with a pop sound when brought close to a lighted splinter. Carbon Dioxide Turns lime water chalky. Chlorine Bleach moist litmus paper. Ammonia Pungent smell. Turn moist red litmus paper to blue. Produces white fume when reacts with concentrated hydrochloric Acid. Sulphur Dioxide Pungent smell. Bleach the purple colour of potassium manganate(vii). Turn moist blue litmus paper to red. Nitrogen Dioxide Pungent smell. Brown in colour. Turn moist blue litmus paper to red. Qualitative analysis Identification of Anions (Negative ions) Diluted HCl or diluted HNO 3 or diluted H 2 SO 4 HCl/HNO 3 CO 3 2 SO 4 2 Carbon Dioxide is released. BaCl (aq) or Ba(NO 3 ) 2 (aq) follow by diluted formed. It is soluble in diluted HCl/HNO 3 formed. It is NOT soluble in diluted HCl/HNO 3 AgNO 3 follow by diluted HNO 3. formed. It is soluble in diluted HNO 3 Brown Ring Test ( + FeSO 4 (aq ) + concentratedh 2 SO 4 Cl NO 3 formed. It is NOT soluble in diluted HNO 3 Formation of Brown Ring 9

10 Idendification of cation NaOH(ak) NH 3 (ak) HCl or NaCl H 2 SO 4 or Na 2 SO 4 Na 2 CO 3 KI Na + Ca 2+ precipitate. Mg 2+ Al 3+ Zn 2+ Pb 2+ Dissolve in excess NaOH solution. Dissolve in excess NaOH solution. Dissolve in excess NaOH solution. Dissolve in excess NH 3 solution. Dissolve in hot water. Yellow Dissolve in hot water Fe 2+ Dirty green Dirty green Green Fe 3+ Red brown Red brown Brown A red brown solution formed. Cu 2+ Blue precipitate is Blue precipitate is Dissolve in excess NH 3 solution and form a blue solution. Blue precipitate is precipitate form in brown solution NH 4 + = No changes is observed 10

11 Distibguish Iron(II) and Iron(III) Reagent Observation Ion presents Solution of potassium hecxacianoferate(ii) Light blue precipitate Fe 2+ Dark Blue precipitate Fe 3+ Solution of potassium hecxacianoferate(iii) Dark blue precipitate Fe 2+ Greenish brown solution Fe 3+ Solution of potassium Thiocyanate(II) Pinkish solution Fe 2+ Blood red solution Fe 3+ Manufactured Substances in Industry Contact Process (Making Sulphuric Acid) Stage 1: Formation of SO 2 Combustion of Sulphur Heating of metal sulphide such as lead(ii) sulphide S (s) + O 2 (g) SO 2 (g) or 2PbS (s) + 3O 2(g) 2PbO (s) + 2SO 2(g) or Combustion of hiydrogen sulphide 2H 2 S (g) + 3O 2(g) 2SO 2(g) + 2H 2 O (ce) Stage 2: Formation of SO 3 2SO 2 (g) + O 2 (g) 2SO 3 (g) Catalyst: vanadium(v) oxide Temperature: 450 C Pressure: 23 atmospheres Stage 3 Formation of oleum H 2 S 2 O 7 Stage 4:Formation of Sulphuric acid SO 3(g) + H 2 SO 4(aq) H 2 S 2 O 7(l) H 2 S (1) + H 2 O (1) 2H 2 SO 4(aq) 11

12 Haber Process (Making Ammonia) Sources of the raw material Hydrogen 1. Reaction between steam and heated coke H 2 O + C CO + H 2 2. Reaction between steam and natural gas. 2H 2 O + CH 4 CO 2 + 4H 2 Nitrogen From distillation of liquid air. The reaction 1. Ammonia is made by the Haber process from nitrogen and hydrogen: N 2 (g) + 3H 2 (g) 2NH 3 (g); ΔH = 92 kj mo1 1 Catalyst: Iron Promoter: Aluminium oxide Temperature: 450 C Pressure: atm 12