5 Equations and quantities

 Converting quantities between different substances using a balanced equation The balancing (stoichiometric) numbers are mole ratios e.g. 1 mole of N2 reacts with 3 moles of H2 to produce 2moles of NH3 Typically we are given a quantity of one substance and are asked to work out a quantity for another substance in the reaction. Any of the above three equations can be used. Step 1: Use one of the above 3 equations to convert any given quantity into moles Mass moles PVT of gas  moles Conc and vol of solution  moles Step 2: Use balanced equation to convert moles of initial substance into moles of second substance Step 3 Convert moles of second substance into quantity question asked for using relevant equation e.g. Moles ,Mr  mass Mole, P, T gas  vol gas Moles, vol solution  conc To turn concentration measured in mol dm-3 into concentration measured in g dm-3 multiply by Mr of the substance conc in g dm-3 = conc in mol dm-3 x Mr The concentration in g dm-3 is the same as the mass of solute dissolved in 1dm3Common Reaction Equations CH3CO2H + NaOH  CH3CO2 -Na+ + H2O H2SO4 + 2NaOH  Na2SO4 +2H2O HCl + NaOH  NaCl +H2O NaHCO3 + HCl  NaCl + CO2 + H2O Na2CO3 + 2HCl 2NaCl + CO2 + H2O CaCO3 + 2HCl  CaCl2 + CO2 + H2O