1. OXIDES Name of the compound Formula 1. 2 3 4 Original Colour Final Colour Residue Gas evolved and test Equation Oxides of potassium, sodium, calcium, magnesium, aluminum, zinc, iron and copper do not decompose on heating. Zinc Oxide ZnO Lead Dioxide PbO2 Red Lead Pb3O4 White Chocolate brown Red Yellow when hot White when cold Yellow Yellow 1 Residue turns white on cooling Does not decompose (only changes colour) Eqn: ZnO ZnO (White) (Yellow) Yellow residue fuses with test tube Oxygen Colourless, odourless neutral gas, rekindles a glowing splinter Eqn: 2PbO2 2PbO + O2 Yellow residue fuses with the test tube Oxygen Colourless, odourless neutral gas, rekindles a glowing splinter Eqn: 2Pb3O4 6PbO +O2 5 6 Mercuric Oxide HgO Silver Oxide Ag2O Red Greyish black Silvery liquid Silver GAS = 2. Silver residue at the bottom of the test tube Oxygen Colourless, odourless neutral gas, rekindles a glowing splinter Eqn: 2Ag2O 4Ag + O2 PRECIPITATE = CARBONATES Name of the compound Formula 1 Silvery mirror on sides of test tube Oxygen Colourless, odourless neutral gas, rekindles a glowing splinter Eqn: 2HgO 2Hg + O2 Original Colour Final Colour Residue Gas evolved test Equation Sodium and Potassium carbonate do not decompose on heating Carbon dioxide 2 Calcium Carbonate CaCO3 White White residue of calcium oxide obtained White Colourless, odourless, slightly acidic to litmus and turns lime water milky Eqn: CaCO3 CaO + CO2 3 Magnesium Carbonate MgCO3 White White residue of magnesium oxide obtained White 2 Carbon dioxide Colourless, odourless, slightly acidic to litmus and turns lime water milky Eqn: MgCO3 MgO + CO2 4 Carbon dioxide Zinc Carbonate ZnCO3 White Yellow residue of zinc Yellow when hot white oxide obtained which when cold turns white on cooling Colourless, odourless, slightly acidic to litmus and turns lime water milky Eqn: ZnCO3 ZnO + CO2 Carbon dioxide 5 Lead Carbonate PbCO3 White Yellow residue fuses with Colourless, odourless, slightly acidic to litmus and turns lime water milky the sides of the test tube Yellow Eqn: PbCO3 PbO + CO2 Carbon dioxide 6 Copper Carbonate CuCO3 Light green Black copper oxide formed Black Colourless, odourless, slightly acidic to litmus and turns lime water milky Eqn: CuCO3 CuO + CO2 Carbon dioxide 7 Ammonium carbonate (NH4)2CO3 White Decomposes on exposure to air and leaves no residue No residue 3 Colourless, odourless, slightly acidic to litmus and turns lime water milky Ammonia Pungent, smelling, basic gas turns red litmus blue and gives dense white fumes with a glass rod of HCl acid Water Vapour Neutral vapours turn Cobalt Chloride paper blue to pink Eqn: (NH4)2CO3 2NH3 + H2O (vap) + CO2 3. BICARBONATES Name of the compound Formula 1 Sodium Bicarbonate NaHCO3 Original Colour White Final Colour Residue White solid sodium carbonate White Gas evolved test Equation Carbon dioxide Colourless, odourless, slightly acidic to litmus and turns lime water milky Water Vapour Neutral vapours turn Cobalt Chloride paper blue to pink Eqn: 2NaHCO3 Na2CO3 + H2O+CO2 4 2 Potassium Bicarbonate KHCO3 White White solid potassium carbonate White Carbon dioxide Colourless, odourless, slightly acidic to litmus and turns lime water milky Water Vapour Neutral vapours turn Cobalt Chloride paper blue to pink Eqn: 2KHCO3 K2CO3 + H2O+CO2 3 Calcium Bicarbonate Ca(HCO3)2 White White Calcium carbonate residue White Carbon dioxide Colourless, odourless, slightly acidic to litmus and turns lime water milky Water Vapour Neutral vapours turn Cobalt Chloride paper blue to pink Eqn: Ca(HCO3) 2 CaCO3 + H2O+CO2 Carbon dioxide Colourless, odourless, slightly acidic to litmus and turns lime water milky 4 Magnesium Bicarbonate Mg(HCO3)2 White White Magnesium carbonate residue White Water Vapour Neutral vapours turn Cobalt Chloride paper blue to pink Eqn: 5 Mg(HCO3) 2 MgCO3 + H2O+ CO2 Note: 4. Calcium bicarbonate and Magnesium bicarbonate exists only in solution NITRATES Name of the compound Formula Original Colour Final Colour Residue Gas evolved test Equation Oxygen 1 Sodium Nitrate NaNO3 Colourless Pale yellow liquid Pale yellow liquid Colourless, odourless neutral gas, rekindles a glowing splinter Eqn: 2NaNO3 2NaNO2 + O2 Oxygen 2 Potassium Nitrate KNO3 Colourless Pale yellow liquid Pale yellow liquid Colourless, odourless neutral gas, rekindles a glowing splinter Eqn: 2KNO3 2KNO2 + O2 Oxygen 3 Calcium Nitrate Ca(NO3)2 Colourless White residue of calcium oxide White Colourless, odourless neutral gas, rekindles a glowing splinter Nitrogen dioxide Reddish brown acidic gas 6 Turns Potassium Iodide paper brown in colour Eqn: 2Ca(NO3)2 2CaO + 4NO2 + O2 4 5 6 Zinc Nitrate Zn(NO3)2 Lead Nitrate Pb(NO3)2 Copper Nitrate Cu(NO3)2 Colourless very deliquescent White deliquescent Blue Salt decrepitates on heating Oxygen Colourless, odourless neutral gas, rekindles a Yellow when hot white White residue of Zinc oxide glowing splinter when cold obtained on cooling Nitrogen dioxide Reddish brown acidic gas Turns Potassium Iodide paper brown in colour Eqn: 2Zn(NO3)2 2ZnO + 4NO2 + O2 Yellow Black 7 Yellow residue of lead monoxide fuses with the test tube Salt decrepitates on heating Oxygen Colourless, odourless neutral gas, rekindles a glowing splinter Nitrogen dioxide Reddish brown acidic gas Turns Potassium Iodide solution brown in colour Eqn: 2Pb(NO3)2 2PbO + 4NO2 + O2 Black residue of copper oxide Oxygen Colourless, odourless neutral gas, rekindles a glowing splinter Nitrogen dioxide Reddish brown acidic gas Turns Potassium Iodide solution brown in colour Eqn: 2Pb(NO3)2 2PbO + 4NO2 + O2 Oxygen Colourless, odourless neutral gas, rekindles a glowing splinter 7 Mercuric Nitrate Colourless Silvery residue of mercury on the test tube Silvery Hg(NO3)2 Nitrogen dioxide Reddish brown acidic gas Turns Potassium Iodide paper brown in colour Eqn: Hg(NO3)2 Hg + 2NO2 + O2 Oxygen Colourless, odourless neutral gas, rekindles a glowing splinter 8 Silver Nitrate Colourless Silvery residue of silver on the test tube Silver AgNO3 Nitrogen dioxide Reddish brown acidic gas Turns Potassium Iodide paper brown in colour Eqn: 2AgNO3 2Ag + 2NO2 + O2 9 Ammonium Nitrate NH4NO3 Nitrous Oxide White Completely disappears on heating No residue 8 (laughing gas) Water Vapour Neutral vapours turn Cobalt Chloride paper blue to pink Eqn: NH4NO3 2H2O + N2O 5. HYDROUS SALTS Name of the compound Formula A Hydrated Copper Sulphate CuSO45H2O B Hydrated Sodium Carbonate Na2CO310H2O 6. a Original Colour Residue Gas evolved test Equation Blue crystalline compound Greyish white residue of copper Sulphate. White anhydrous powder On strong heating the residue turns black Water vapour Neutral vapours turn Cobalt Chloride paper blue to pink Eqn: CuSO45H2O CuSO4 + 5H2O White crystalline solid White anhydrous White anhydrous powder residue of sodium carbonate Water vapour Neutral vapours turn Cobalt Chloride paper blue to pink Eqn: Na2CO310H2O : Na2CO3 + 10H2O Orange Decomposes with sparks giving out heat and Green powder of forms a green fluffy chromic oxide powder Water vapour Neutral vapours turn Cobalt Chloride paper blue to pink Nitrogen Colourless neutral gas Eqn: (NH4)2Cr2O7 : Cr2O3 + N2 + 4H2O Disappears from the bottom of the test tube and settles down as a Ammonia Basic gas turns red litmus blue and gives dense white fumes with a glass rod dipped in HCl Other compounds Ammonium dichromate (NH4)2Cr2O7 b Final Colour Ammonium Chloride White solid No residue at the bottom of the test tube 9 NH4Cl white solid on the upper cooler parts of the test tube Hydrogen Chloride An acidic gas gives dense white fumes with a glass rod dipped in Ammonium Hydroxide Eqn: NH4Cl NH3+ HCl Iodine – Camphor – Naphthalene do not undergo any chemical change when heated, but undergo sublimation Eg: Iodine crystals Iodine vapour 10
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