potassium carbonate  potassium oxide + carbon dioxide zinc hydroxide  zinc oxide + water iron(II) hydroxide  iron(II) oxide + water nickel(II) chlorate  nickel(II) chloride + oxygen sodium chlorate  sodium chloride + oxygen potassium chlorate  potassium chloride + oxygen sulfuric acid  water + sulfur trioxide carbonic acid  + carbon dioxide aluminium oxide  aluminium + oxygen silver oxide  silver + oxygen Synthesis Reactions In synthesis reactions, two or more reactants come together to form one compound, following the general pattern: A + B AB Write the formula equation for the following synthesis reactions. calcium + oxygen  calcium oxide copper + sulfur  copper(II) sulfide
calcium + water  calcium hydroxide hydrogen + nitrogen  ammonia hydrogen + chlorine  hydrogen chloride silver + sulfur  silver sulfide chromium + oxygen  chromium(III) oxide aluminium + bromine  aluminium bromide sodium + iodine  sodium iodide hydrogen + oxygen  water aluminium + oxygen  aluminium oxide Synthesis and Decomposition Reactions For each reaction below, (i) identify it as either a synthesis (S) or decomposition (D) reaction, (ii) write each chemical formula to complete the equation in full. potassium + oxygen → potassium oxide calcium + oxygen → calcium oxide
barium carbonate → barium oxide + carbon dioxide lithium + sulfur → lithium sulfide magnesium chlorate → magnesium chloride + oxygen strontium + nitrogen → strontium nitride potassium + bromine → potassium bromide sodium chlorate → sodium chloride + oxygen hydrogen + iodine → hydrogen iodide calcium chloride → calcium + chlorine Answers Decomposition barium carbonate  barium oxide + carbon dioxide BaCO3  BaO + CO2 magnesium carbonate  magnesium oxide + carbon dioxide MgCO3  MgO + CO2 potassium carbonate  potassium oxide + carbon dioxide K2CO3  K2O + CO2 zinc hydroxide  zinc + water Zn(OH)2  ZnO + H2O
iron(II) hydroxide  iron(II) + water Fe(OH)2  FeO + H2O nickel(II) chlorate  nickel(II) chloride + oxygen Ni(ClO3)2  + 3O2 sodium chlorate  sodium chloride + oxygen 2NaClO3  2NaCl + 3O2 potassium chlorate  potassium chloride + oxygen 2KClO3  2KCl + 3O2 sulfuric acid  water + sulfur trioxide  H2O + SO3 carbonic acid  water + carbon dioxide H2CO3  H2O + CO2 aluminium oxide  aluminium + oxygen 2Al2O3  4Al + 3O2 silver oxide  silver + oxygen 2Ag2O  4Ag + O2 Answers Synthesis calcium + oxygen  calcium 2Ca + O2  2CaO copper + sulfur  copper(II) sulfide 8Cu + S8  8CuS calcium oxide + water  calcium hydroxide CaO + H2O  Ca(OH)2 hydrogen + nitrogen  ammonia 3H2 + N2  2NH3 hydrogen + chlorine  hydrogen chloride
H2 + Cl2  2HCl silver + sulfur  silver sulfide 16Ag + S8  8Ag2S chromium + oxygen  chromium(III) 4Cr + 3O2  2Cr2O3 aluminium + bromine  aluminium bromide 2Al + 3Br2  2AlBr3 sodium + iodine  sodium iodide 2Na + I2  2NaI hydrogen + oxygen  water 2H2 + O2  2H2O aluminium + oxygen  aluminium oxide 4Al + 3O2  2Al2O3 Acid reactions acid + metal hydroxide, acid + metal oxide, acid + carbonate (Oxford 4.2) Acid reactions Acids almost always have a ‘H’ at the front of their formula (it is this that forms H+ ions) Some common ones you should know are: Hydrochloric acid (HCl), Nitric acid (HNO3) and sulphuric acid (H2SO4) Bases almost always have ‘O’ or ‘OH’ at the end of their formula (they react with water to form OH- ions). Some common ones you should know are: Sodium Hydroxide (NaOH), Ammonia (NH3 –an exception to our rule) and iron oxide (Fe2O3) Carbonates always have ‘CO3’ at the end of their formula (it is this that makes CO2 when it reacts with acid) Some common ones are: Calcium carbonate (CaCO3), sodium Carbonate (Na2CO3) and Sodium Hydrogencarbonate (NaHCO3) Identify the formula below as acid, metal, base or carbonate: