This solubility table is a 'secret' contributed by Ms Aida (BtVSS, MOE Singapore)
Cation test with NaOH
Cu2+
Fe2+
Fe3+
Ca2+
NH4+
Zn2+
Al3+
Pb2+
Cation test with NH3
Cu2+
Fe2+
Fe3+
Zn2+
Al3+
Pb2+
Cation test table
Shows colour changes when salts are added to NaOH or NH3
Anion tests
Chloride (AgNO3 - white ppt)
Carbonate (CO2 - turns limewater chalky)
Sulfate (Ba(NO3)2 - white ppt)
Nitrate (Al, NaOH - turns red litmus blue)
Iodide (Pb(NO3)2 - yellow ppt)
Gas tests
Ammonia (damp litmus paper turns blue)
Carbon dioxide (limewater turns chalky)
Chlorine (damp blue litmus paper bleaches)
Hydrogen (burning splint makes 'pop' sound)
Oxygen (glowing splint glows brighter/bursts into flame)
Sulfur dioxide (K2Cr2O7 turns green)
Mole concept formulas
Mass of sample
Volume of gas
Number of moles
Number of particles
All acids change blue litmus red
Acids react with metals above hydrogen in reactivity series
Acids react with bases to form salt and water
Uses of ammonia
Manufacture of nitric acid
Produce fertilisers
Hydrogen can be used as a fuel
Ethene (alkene) is used to make plastic
Potassium dichromate (VI)
Acts as an oxidising agent
Turns from orange to green when oxidised
Potassium iodide
Acts as a reducing agent
Turns from colourless to brown when reduced
Uses of ethanol
Solvent for organic compounds
To make alcoholic drinks
Something with more carbon content is stronger
Fermentation
Requires 37°C, enzymes, no oxygen
Alkene addition of steam to become alcohol
Requires phosphoric acid catalyst, 300°C, high temperature/pressure
Alkene addition of hydrogen to become alkane
Requires nickel catalyst
Fractional distillation of petroleum
Crude oil boiled, lighter fractions separate at lower boiling points, heavier fractions separate at higher boiling points, fractions collected at different boiling points
Electrical conductivity
Requires moving ions
Heat conductivity
Requires free moving electrons
Boiling point
Depends on strength of electrostatic attraction
Why ionic compounds have high boiling point
Consist of ions held by strong electrostatic attraction, large energy needed to break bonds
Why covalent compounds have low boiling point
Consist of molecules with weak intermolecular forces, small energy needed to break bonds
Why ionic compounds conduct in molten/aqueous state
Ions become free to move and convey charge
Why ionic compounds cannot conduct in solid state
Ions are fixed rigidly by strong electrostatic attraction and cannot move
Why attaching magnesium to iron pipes increases their working life
Magnesium is more reactive than iron, so water reacts with magnesium instead, reducing iron rusting (sacrificial protection)
Why copper cannot be used instead of magnesium for sacrificial protection
Copper is less reactive than iron, so iron would rust faster with copper attached
Why hydrogen is more reactive than helium
Hydrogen has 1 valence electron and can gain 1 more to become stable, helium has 2 valence electrons and is very stable
Physical properties of metals
Good conductors of heat and electricity
High boiling and melting points
Malleable and ductile
Why copper is recycled
Copper is expensive and not as abundant as some other metals
When naming an ester, you need to consider the structure