CHem

ONE-SCHOOL.NET Short Notes: Form 4 Chemistry Chemical Formulae and Equation Calculation For Solid, liquid or gas For gas (only) number of mole = mass of subtance molar mass number of mole = volume of gas molar volme Molar mass = RAM/RMM/RFM in gram Molar volume = 24dm3 at room temperature Molar volume = 22.4dm3 at s.t.p. For Solution For quantity of particle(atom,molecule,ion) number of mole = MV 1000 number of mole = quantity of particle 6.02 ×1023 M = molarity V = Volume of solution in cm3 Summary ÷ molar mass Mass of particle (in gram) × molar mass × Avogadro Constant Mole of particles Avogadro Constant × molar volume ÷ molar volume Volume of Gas http://one-school.net/notes.html Number of particles 1 ONE-SCHOOL.NET Chemical Formula Cation (Positive Ions) Ion Potassium Symbol K+ Ion Calcium Symbol Ca2+ Ion Aluminium Symbol Al3+ Sodium Na+ Magnesium Mg2+ Iron (III) Fe3+ Lithium Li+ Zinc Zn2+ Chromium(III) Cr3+ Hydrogen H+ Barium Ba2+ Argentums(I) Ag+ Iron (II) Fe2+ Mercury(I) Hg+ Tin (II) Sn2+ Ammonium NH4+ Lead(II) Pb2+ Copper(II) Cu2+ Manganese(II) Mn2+ Ion Symbol Ion Symbol Anion (Negative Ions) Ion Symbol Oxide O2- Hydroxide OH- Ethanoate Fluoride F- Sulphate SO42- Manganate(VII) MnO4- Chloride Cl- Nitrate NO3- Dichromate(VI) Cr2O72- Bromide Br- Carbonate CO32- Phosphate PO43- Thiosulphate S2O32- Iodide I- CH3COO- Formulae for Certain Molecule Karbon monoxide Carbon dioxide Nitrogen monoxide Nitrogen dioxide Sulphur dioxide Sulphur trioxide Fluorine Bromine Chlorine Iodine http://one-school.net/notes.html CO CO2 NO NO2 SO2 SO3 F2 Br2 Cl2 I2 Ammonia water Hydrogen chloride Tetrachloromethane Glucose Hydrogen bromide Hydrogen iodide Hydrogen sulphide Ethanol Ethanoic Acid 2 NH3 H2O HCl CCl4 C6H12O6 HBr HI H2S C2H5OH CH3COOH ONE-SCHOOL.NET Periodic Table Reaction of Group 1 Elements 1. Reaction with Oxygen The entire group 1 metal can react with oxygen to form metal oxide. 4Li + O2 ⎯→ 2Li2O 4Na + O2 ⎯→ 2Na2O 4K + O2 ⎯→ 2K2O Li2O + H2O ⎯→ 2LiOH Na2O + H2O ⎯→ 2NaOH K2O + H2O ⎯→ 2KOH The metal oxide of group 1 elements can dissolve in water to form alkali (hydroxide) solution 2. Reaction with halogen (Chlorine) 2Li + Cl2 ⎯→ 2LiCl 2Na + Cl2 ⎯→ 2NaCl 2K + Cl2 ⎯→ 2KCl 3. Reaction with water The entire group 1 metal can react with water to produce alkali (hydroxide) solution and hydrogen gas. 2Li + 2H2O ⎯→ 2LiOH + H2 2Na + 2H2O ⎯→ 2NaOH + H2 2K + 2H2O ⎯→ 2KOH + H2 Reaction of Group 17 Elements 1. React with water Cl2 + H2O ⎯→ HCl + HOCl Br2 + H2O ⎯→ HBr + HOBr I2 + H2O ⎯→ HI + HOI 2. React with Sodium Hydroxide Cl2 + 2NaOH ⎯→ NaCl + NaOCl + H2O Br2 + 2NaOH ⎯→ NaBr + NaOBr + H2O I2 + 2NaOH ⎯→ NaI + NaOI + H2O 3Cl2 + 2Fe ⎯→ 2FeCl3 3Br2 + 2Fe ⎯→ 2FeBr3 3I2 + 2Fe ⎯→ 2FeI3 3. React with Iron 2KMnO4 + 16HCl ⎯→ 2KCl + 2MnCl2 + 5Cl2 + 8H2O Preparation of Chlorine Gas http://one-school.net/notes.html 3 ONE-SCHOOL.NET Electrochemistry Electrolyte Ionisation of Electrolyte Ionisation of Molten Compound Ionisation of Aqueous Solution NaCl ⎯→ Na+ + ClH2O ⎯→ H+ + OH- PbBr2 ⎯→ Pb2+ + BrNaCl ⎯→ Na+ + ClAl2O3 ⎯→ 2Al3+ + 3O2HCl ⎯→ H+ + ClH2O ⎯→ H+ + OH- Na + e ⎯→ Na CuSO4 ⎯→ Cu2+ + SO42H2O ⎯→ H+ + OH2Cl- ⎯→ Cl2 + 2e Discharge of Positive Ion Discharge of Negative Ion + Observation: Grey deposit is formed. Observation: Bubbles of pungent yellowish green gas are produced. The gas turns moist litmus paper to red and then bleaches it. Al3+ + 3e ⎯→ Al 2Br- ⎯→ Br2 + 2e Observation: Grey deposit is formed. Pb + 2e ⎯→ Pb Observation: Molten electrolyte: Brown colour gas is produced. Cu + 2e ⎯→ Cu Aqueous solution: Light brown solution is formed. 2+ Observation: Grey deposit is formed. 2+ 2I- ⎯→ I2 + 2e Observation: Brown deposit is formed. Ag+ + e ⎯→ Ag Observation: Molten electrolyte: Brown colour gas is produced. 2H+ + 2e ⎯→ H2 Aqueous solution: Light brown solution is formed. The solution turns blue when a few drops of starch solution is added in. Observation: Silver deposit is formed. Observation: Gas bubble is formed. A ‘pop’ sound is produced 4OH- ⎯→ O2 + 2H2O + 4e when a lighted splinter is placed near the mouth of Observation: the test tube. Gas bubble is formed. Gas produces light up a wooden splinter. http://one-school.net/notes.html 4 ONE-SCHOOL.NET Acid and Base Ionisation of Acid HCl ⎯→ H + Cl HCl + H2O ⎯→ H3O+ + Cl- H2SO4 ⎯→ H+ + SO42H2SO4 + 2H2O ⎯→ 2H3O+ + SO42- Hydrochloric Acid + Sulphuric Acid - HNO3 ⎯→ H+ + NO3HNO3 + H2O ⎯→ H3O+ + NO3Nitric Acid CH3COOH ⎯→ H+ + CH3COOCH3COOH + H2O ⎯→ H3O+ + CH3COOEthanoic Acid Chemical Properties of Acid Acid + Reactive Metal ⎯→ Salt + H2 2HCl + Zn ⎯→ ZnCl2 + H2 6HNO3 + 2Fe ⎯→ 2Fe(NO3)3 + 3H2 H2SO4 + Pb⎯→ PbSO4 + H2 6CH3COOH + 2Al ⎯→ 2Al(CH3COO)3 + 3H2 Example: Acid + Metal Oxide⎯→ Salt + H2O 2HCl + ZnO ⎯→ ZnCl2 + H2O 2HNO3 + MgO ⎯→ Mg(NO3)2 + H2O H2SO4 + CuO ⎯→ CuSO4 + H2O 2CH3COOH + Na2O ⎯→ 2CH3COO-Na++ H2O Example: Acid + Metal Hydroxide⎯→ Salt + H2O 2HCl + Ca(OH)2 ⎯→ CaCl2 + 2H2O HNO3 + NaOH⎯→ NaNO3 + H2O H2SO4 + 2NH4OH ⎯→ (NH4)2SO4 + 2H2O or - + CH3COOH + KOH ⎯→ CH3COO K + H2O Example: Acid + Metal Carbonate ⎯→ Salt + CO2 + H2O H2SO4 + 2NH3 ⎯→ (NH4)2SO4 2HCl + ZnCO3 ⎯→ ZnCl2 + CO2 + H2O 2HNO3 + CaCO3 ⎯→ Ca(NO3)2 + CO2 + H2O H2SO4 + Na2CO3 ⎯→ Na2SO4 + CO2 + H2O 2CH3COOH + MgCO3 ⎯→ Mg(CH3COO)2 + CO2 + H2O Example: http://one-school.net/notes.html 5 ONE-SCHOOL.NET Salt Solubility of Salt Salt Salt of potassium, sodium and ammonium Salt of nitrate Salt of sulphate Salt of chloride Salt of carbonate Oxide and Hydroxide Oxide Hydroxide Solubility All are soluble in water All are soluble in water Mostly soluble in water except: (Pb) Lead sulphate (Ba) Barium sulphate (Ca) Calcium sulphate Mostly soluble in water except: (Pb) Lead chloride (Ag) silver chloride (Hg) mercury chloride Mostly insoluble in water except: Potassium carbonate Sodium carbonate Ammonium carbonate Solubility Mostly insoluble in water except: K2O and Na2O. Mostly insoluble in water except: NH4OH, 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 + H2O Salt of non-Potassium, 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 (ZnSO4) H2SO4 + Zn ⎯→ ZnSO4 + H2 H2SO4 + ZnO ⎯→ ZnSO4 + H2O H2SO4 + ZnCO3 ⎯→ ZnSO4 + H2O + CO2 http://one-school.net/notes.html 6 ONE-SCHOOL.NET 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. AgNO3 (aq) + NaCl (aq) ⎯→ AgCl (s) + NaNO3 (aq) Ag+ (aq) + C1- (aq) ⎯→ AgCl (s) (ionic equation) Example: Preparation of Silver Nitrate Colour of Salt Salt or metal oxide Salt of: Sodium, Calcium, Magnesium, Aluminium, zinc, Lead, ammonium Chloride, sulphate, nitrate, carbonate Salt of Copper(II).Copper(II) Carbonate Copper(II) sulphate, Copper(II) nitrate, Copper(II) chloride Copper(II) oxide Salt of Iron (II) Iron(II) sulphate; Iron(II) nitrate; Iron(ID chloride Salt of Iron (III). Iron(III) sulphate; Iron(III) nitrate; Iron(III) chloride Lead Iodide Lead Chloride Zink oxide Lead(II) oxideMagnesium oxide, Aluminium oxide Potassium oxide, Sodium oxide, Calcium oxide http://one-school.net/notes.html 7 Solid Aqueous solution White Colourless Green Insoluble Blue Blue Black Insoluble Green Green Brown Brown Yellow White Yellow when it is hot and white when it is cold. Brown when it is hot and yellow when it is cold. White White Insoluble Insoluble Insoluble Insoluble Insoluble Colourless ONE-SCHOOL.NET Heating effect on Salt Heating Effect CO32- NO3 - SO42- Cl- Most Probably Release CO2 Most Probably Release NO2 Most Probably Release SO3 Most Probably No effect 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 Mercury(II) carbonate Silver(I) carbonate Ammonium carbonate Not decomposible CaCO3 ⎯→ CaO + CO2 MgCO3 ⎯→ MgO + CO2 Al2(CO3)3 ⎯→ Al2O3 + 3CO2 ZnCO3 ⎯→ ZnO + CO2 Fe2(CO3)3⎯→ Fe2O3 + 3CO2 PbCO3 ⎯→ PbO + CO2 CuCO3 ⎯→ CuO + CO2 2HgCO3 ⎯→ 2Hg + 2CO2 + O2 2Ag2CO3 ⎯→ 4Ag + 2CO2 + O2 (NH4)2CO3 ⎯→ NH3 + CO2 + H2O Heating Effect on Nitrate Salt Nitrate Salt Equation of The Reaction Potassium nitrate 2KNO3 ⎯→ 2KNO2 + O2 Sodium nitrate 2NaNO3 ⎯→ 2NaNO2 + O2 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 2Ca(NO3)2 ⎯→ 2CaO + 4NO2 + O2 Mg(NO3)2 ⎯→ 2MgO + 4NO2 + O2 4Al(NO3)3 ⎯→ 2Al2O3 + 12NO2 + 3O2 Zn(NO3)2 ⎯→ 2ZnO + 4NO2 + O2 4Fe(NO3)3⎯→ 2Fe2O3 + 12NO2 + 3O2 Pb(NO3)2 ⎯→ 2PbO + 4NO2 + O2 Cu(NO3)2 ⎯→ 2CuO + 4NO2 + O2 Hg(NO3)2 ⎯→ Hg + 2NO2 + O2 2AgNO3 ⎯→ 2Ag + 2NO2 + O2 NH4NO3 ⎯→ N2O + 2H2O [NOTES: Nitrogen dioxide, NO2 is acidic gas and is brown in colour.] http://one-school.net/notes.html 8 ONE-SCHOOL.NET 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 The heating effect on chloride salts All chloride salts are not decomposable by heat except ammonium chloride. Example: NH4Cl ⎯→ NH3 + HCl ZnSO4 ⎯→ ZnO + SO3 CuSO4 ⎯→ CuO + SO3 2Fe2(SO4)3⎯→ Fe2O3 + SO2 + SO3 (NH4)2SO4 ⎯⎯→ 2NH3 + H2SO4 Ammonium sulphate Identification of Gases Gasses Oxygen Hydrogen Carbon Dioxide Chlorine Ammonia Characteristics Rekindle glowing splinter. Explode with a ‘pop’ sound when brought close to a lighted splinter. Turns lime water chalky. Bleach moist litmus paper. Pungent smell. Turn moist red litmus paper to blue. Produces white fume when reacts with concentrated hydrochloric Acid. Pungent smell. Bleach the purple colour of potassium manganate(VII). Turn moist blue litmus paper to red. Pungent smell. Brown in colour. Turn moist blue litmus paper to red. Sulphur Dioxide Nitrogen Dioxide Qualitative analysis Identification of Anions (Negative ions) Diluted HCl or BaCl (aq) or Ba(NO3)2 AgNO3 follow by Brown Ring Test diluted HNO3 or (aq) follow by diluted diluted HNO3. ( + FeSO4 (aq ) + diluted H2SO4 HCl/HNO3 concentratedH2SO4 White precipitate is White precipitate is formed. It is soluble in Carbon Dioxide is 2formed. It is soluble in CO3 released. diluted HCl/HNO3 diluted HNO3 2- SO4 - White precipitate is formed. It is NOT soluble in diluted HCl/HNO3 - - Formation of Brown Ring Cl- - - White precipitate is formed. It is NOT soluble in diluted HNO3 NO3- - - - http://one-school.net/notes.html 9 ONE-SCHOOL.NET Idendification of cation NaOH(ak) NH3(ak) HCl or NaCl H2SO4 or Na2SO4 Na2CO3 White precipitate is produced. White precipitate is produced. KI Na+ Ca2+ White precipitate. Mg2+ White precipitate is produced. Al3+ Zn2+ Pb2+ Fe2+ Fe 3+ 2+ Cu White precipitate is produced. Dissolve in excess NaOH solution. White precipitate is produced. Dissolve in excess NaOH solution. White precipitate is produced. Dissolve in excess NaOH solution. White precipitate is produced. White precipitate is produced. White precipitate is produced. White precipitate is produced. . White precipitate is produced. Dissolve in excess NH3 solution. White precipitate is produced. White precipitate is produced. White precipitate is produced. Dissolve in hot water White precipitate is produced. White precipitate is produced. Yellow precipitate is produced. Dissolve in hot water Dirty green precipitate is produced. Dirty green precipitate is produced. Green precipitate is produced. Red brown precipitate is produced. Red brown precipitate is produced. Brown precipitate is produced. A red brown solution formed. Blue precipitate is produced. Blue precipitate is produced. Dissolve in excess NH3 solution and form a blue solution. Blue precipitate is produced. White precipitate form in brown solution NH4+ = No changes is observed http://one-school.net/notes.html 10 ONE-SCHOOL.NET Distibguish Iron(II) and Iron(III) Reagent Solution of potassium hecxacianoferate(II) Solution of potassium hecxacianoferate(III) Solution of potassium Thiocyanate(II) Observation Light blue precipitate Dark Blue precipitate Dark blue precipitate Greenish brown solution Pinkish solution Blood red solution Ion presents Fe2+ Fe3+ Fe2+ Fe3+ Fe2+ Fe3+ Manufactured Substances in Industry Contact Process (Making Sulphuric Acid) Stage 1: Formation of SO2 Combustion of Sulphur S (s) + O2 (g) ⎯⎯→ SO2 (g) or Heating of metal sulphide such as lead(II) sulphide 2PbS(s) + 3O2(g) ⎯⎯→ 2PbO(s) + 2SO2(g) or 2H2S(g) + 3O2(g) ⎯⎯→ 2SO2(g) + 2H2O(ce) Combustion of hiydrogen sulphide Stage 2: Formation of SO3 2SO2 (g) + O2 (g) ⎯⎯→ 2SO3 (g) Catalyst: vanadium(V) oxide Temperature: 450°C Pressure: 2-3 atmospheres Stage 3 Formation of oleum H2S2O7 SO3(g) + H2SO4(aq) ⎯⎯→ H2S2O7(l) Stage 4:Formation of Sulphuric acid H2S207 (1) + H2O (1) ⎯⎯→ 2H2SO4(aq) http://one-school.net/notes.html 11 ONE-SCHOOL.NET Haber Process (Making Ammonia) Sources of the raw material Hydrogen 1. Reaction between steam and heated coke H2O + C ⎯→ CO + H2 2. Reaction between steam and natural gas. 2H 2 O + CH 4 ⎯→ CO2 + 4H2 Nitrogen From distillation of liquid air. The reaction 1. Ammonia is made by the Haber process from nitrogen and hydrogen: N2(g) + 3H2(g) ⎯→ 2NH3(g); ΔH = -92 kJ mo1-1 Catalyst: Iron Promoter: Aluminium oxide Temperature: 450 °C Pressure: 200-1000 atm http://one-school.net/notes.html 12