# Unit C5

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• Unit C5 quantive analysis
• acids and akilies
• hydrocloric acid = HCl
• nirric acid HNO3
• sulfric acid H2SO4
• soudium hydroxide NAOH
• an acid with a lower ph is stronger than an acid with a higher ph
• titrations
• these are used to find the contations of an unknown acid
• this is found using a known contraition and adding a indicator for example phenolthaline that will change immediately
• once you have found the amount you must convert it into decimetres cubed to find the concentration
• titration equation
• work out the hydrogen to hydroxide ratio
• then work out the amount yuou need to nutrlise the other substance baised off the ration convert this to decimters
• then use this equation amount of moles / volume to get concentration
• neutralisation is H+ + OH-____>H2O
• important equation conc=amount of moles /vol
• single change indicators should be used as they give a more clear colour change
• empirical formulae and % composition
• how to do a empirical formulae  equation divide the amount by its MR to get the to number then get the smallest number say you divide h20 with 50% oxygen and 25% hydrogen so 50/1 = 50 25/ 16 =1.5625 you would divide both of these numbers by 1.5625 to get the number then you work this out in a ratio  for water 2 hydrogen to one oxygen giving H2o
• this is the simplest number ratio for the chemical for example glucose is CH2O
• the % com is how much one substance is of an element
• for example find the % com of oxygen in 40n g of MgO so you do 16/40x100 to get 40%
• solutions and concentrations and quantive analysis
• solution = a solute dissolved in a solvent
• concentration =the strength of a substance the amount of solute in a given volume of solvent
• a decimetre is the standard volume of measurement when dealing with concentrations
• it is equivalent to 1000 cm cubed
• the contrition of a solution is measured in mols per dm cubed  or in G/dm3
• knowing about mols is important as it helps with things like making orange juice or baby milk
• gas volumes
• as many reaction HAVE A GAS AS A PRODUCT IT NEEDS TO BE MESSURED SO IOLUMES AS THIS IS TYHE EAISYEST WAY TO DO THIS
• to measure this you can use a upturned cylinder or burette but for the most accurate results you should use a gas syringe
• thwe amount of gas produced will be decided by the limiting factor so the lower the limiting factor the less gas will be produced
• to work out gas molarity you need to replace molar mass with 24dm 3
• equilibrium and the contact proses
• this happens during reversabel reactions
• it means THE FOWARD REACTION IS EQUAL TO THE BACIKWARDS REACTION
• this can happen because it is not a closed system at first the rate of the forward decreases and they backward increases and they become equal
• adding  a extra product increasing temperature pressure all effect equilibrium
• this process is used to create sulphuric acid
• water sulphur and oxygen
• stage 2= suphur + oxygen ----> sulphur dioxide
• stage two more oxygen ids added to make the substance sulphur trioxide this is a reversible reaction
• you also need 450oc of heat a vanadium oxide catalysis and atmospheric pressure
• a change in any of these may change the equilibrium
• precipitation reactions and ionic equations
• most precipitation reactions involve ions form one solution reacting with ions from another solution
• chlorine reform a white precipitate bromine form A cream precipitate and iodine forms a yellow precipitate
• precipitation reactions are extremely fast
• you cab test form sulphate ions using barium chloride
• this is because it is more ionsing this is strength of the acid this has nothing to do with concentration
• an acid with a lower ph is stronger than an acid with a higher ph