The Formula of Succinic Acid :: GCSE Chemistry Coursework Investigation

The Formula of Succinic AcidSuccinic acid is a diprotic, which means it donates deuce protons permolecule. Succinic acid can be completely kill by sodiumhydroxide. The indicator most suitable for this experiment isphenolphthalein, it is colourless in acids and pink in alkalises. Thehalf way stage is about pH 9.3, this is when it will either changefrom colourless to a very pale pink or from pink to colourless. Todetermine the relative formula mass of succinic acid I am going to doa titration against sodium hydroxide. The equation for the reaction is given below. To make the equationeasier to read, HOOC(CH2)nCOOH will be condensed to H2A because of thetwo hydrogen atoms at either end.H2A+2NaOH Na2A+2H2O(CV) H2A = 1(CV) NaOH 2I am going to use the NaOH as 0.1M because I dont want it in additionconcentrated, so thusly I am going to use H2A as 0.05M because ofthe ratio 21.In the formula of succinic acid below n is a whole number between 1and 4. So therefore first I need to calculate th e relative molecularmass of succinic acid.HOOC(CH2)nCOOH H = 1 O = 16 C = 12Mr when n = 1 1+16+16+12 (12+2) 12+16+16+1 = 104Mr when n = 2 1+16+16+12 (12+2) x2 12+16+16+1 = 118Mr when n = 3 1+16+16+12 (12+2) x3 12+16+16+1 = 132Mr when n = 4 1+16+16+12 (12+2) x4 12+16+16+1 = 146From these calculations I can see that I need between 104g and 146g in1 litre to equal 1M. But I want the event in 250cm3, so therefore Ineed to divide the weights by 4n = 1 104 = 26g So I need between 26g and 36.5g in 250cm3to make a 1M4 solution.n = 4 146 = 36.5g4I also want to make the solution to 0.05M because of the ratio 21, sotherefore I need to multiply each weight by 0.05.n = 1 26 x 0.05 = 1.3g n = 4 36.5 x 0.05 = 1.8205g So the crop I can work with to weigh out the anhydrous succinic acidis from 1.3g to 1.82g,which will make a 0.05M solution in 250cm3.Preparing a monetary standard solution=============================Having calculated the weight I can use (1.3g-1.82g), I must weigh outthe solut e using an accurate electronic balance that goes to collardecimal places. I must make sure I clean the balance with a finebrush assuming that it may not hit been cleaned after the last timeit was used and set the balance back to 0.