2024 Sec 3 Chem Notes (For circulation)

Upper Secondary Pure Chemistry

QA notes: will be given during practical 6092 CHEMISTRY GCE ORDINARY LEVEL SYLLABUS 30 NOTES FOR QUALITATIVE ANALYSIS Test for anions anion test test result carbonate (CO32–) add dilute acid effervescence, carbon dioxide produced chloride (Cl –) [in solution] acidify with dilute nitric acid, then add aqueous silver nitrate white ppt. iodide (I–) [in solution] acidify with dilute nitric acid, then add aqueous silver nitrate yellow ppt. nitrate (NO3–) [in solution] add aqueous sodium hydroxide, then aluminium foil; warm carefully ammonia produced sulfate (SO42–) [in solution] acidify with dilute nitric acid, then add aqueous barium nitrate white ppt. Test for aqueous cations cation effect of aqueous sodium hydroxide effect of aqueous ammonia aluminium (Al 3+) white ppt., soluble in excess giving a colourless solution white ppt., insoluble in excess ammonium (NH4+) ammonia produced on warming – calcium (Ca2+) white ppt., insoluble in excess no ppt. copper(II) (Cu2+) light blue ppt., insoluble in excess li ght blue ppt., soluble in excess giving a dark blue solution iron(II) (Fe2+) green ppt., insoluble in excess green ppt., insoluble in excess iron(III) (Fe3+) red-brown ppt., insoluble in excess red-brown ppt., insoluble in excess zinc (Zn2+) white ppt., soluble in excess giving a colourless solution white ppt., soluble in excess giving a colourless solution Test for gases gas test and test result ammonia (NH3) turns damp red litmus paper blue carbon dioxide (CO2) gives white ppt. with limewater (ppt. dissolves with excess CO2) chlorine (Cl2) bleaches damp litmus paper hydrogen (H2) ‘pops’ with a lighted splint oxygen (O2) relights a glowing splint sulfur dioxide (SO2) turns aqueous acidified potassium manganate(VII) from purple to colourless

Chapter 1: Experimental Chemistry Apparatus Pipette Measures accurate fixed volumes (e.g. 10.0cm3 or 25.0cm3) – 1 d.p. Volumetric Flask Measures accurate fixed volumes that are larger (e.g. 100 cm3 or 250 cm3) Measuring Cylinder Measures a range of volumes to the nearest 0.5 cm3 (e.g. 31.5 cm3 or 23.0 cm3) Burette Measures a range of volumes to the nearest 0.05 cm3 (e.g. 31.55 cm3 or 23.00 cm3) – most accurate (when 2 dp value, usually burette) Collection Method Water Displacement Gas must be insoluble/slightly soluble in water (e.g. Hydrogen, Oxygen, Carbon Dioxide) Downward Delivery Gas must be denser than air – Mr/Ar > 28 (e.g. chlorine, hydrogen chloride, sulfur dioxide) Upward Delivery Gas must be less dense than air – Mr/Ar < 28 (e.g. Ammonia, helium, hydrogen) Drying Agent Concentrated Sulfuric Acid Most gases except basic gas (e.g. ammonia) Quicklime (Calcium Oxide) Gases (ammonia can be dried here) except acidic gases (e.g. Sulfur Dioxide, Carbon Dioxide, Nitrogen Dioxide, Chlorine, Hydrogen Chlorine) Fused Calcium Chloride Gases except those who react with Calcium Chloride (e.g. Am