Making Copper (II) Sulphate Stock Solution evaluation

Number of moles =         Mass
                                      Molar Mass
                             n =   m
                                    Mr
                             n =      24.954
                                         249.6
                            n = 0.099975961 mol

Now I know how many moles of CuSO4 I have I can work out the concentration of the solution (CuSO4.5H2O) I have made up with distilled water in the 1dm3 flask by using the equation:

                                                       Concentration =  Number of Moles
                                                                                            Volume
                                                                              c = n
                                                                                    v
                                                  c of CuSO4.5H2O =  0.099975961 mol
                                                                                                 1

                                                                                = 0.099975961 mol dm-3
                                                                                 = 0.100 mol dm-3 (3sf )

Due to the apparatus I used in the experiment there is a possibility that the concentration I have calculated is not exactly right; this is known as the precision error. To calculate the precision error I need to calculate the percentage uncertainty of each piece of apparatus that I used and then add them all together to give a total percentage uncertainty:

% uncertainty of the 3dp balance = (5 x 10-4) x 2 =    0.001     x 100
                                                                                          24.954g
                                                            = 4 x 10-3 %

% uncertainty of the 1dm3 flask     =    0.8     x 100
                                                                1000
                                                            = 0.08 %

Therefore the total uncertainty     = 0.08 % + 4 x 10-3 %
                                                            = 0.084 %

So, to work out the percentage error I need to work out the percentage of the concentration that could be incorrect:

                                  Percentage Error = Total uncertainty   x Concentration
                                                                               100
                                                                =  0.084  x 0.099975961 mol dm-3
                                                                                                        100
                                                                = ± 8.397980724 x 10-5     

Now that I have the percentage error I can show the possible errors that there could be in the calculation of the concentration of CuSO4.5H2O:

Highest possible c of CuSO4.5H2O = 0.10005994mol dm-3     
Lowest possible c of CuSO4.5H2O   = 0.099891981 mol dm-3

However I will represent the final concentration I have calculated of the CuSO4.5H2O  as:

x 0.099975961 ± 8.397980724 x 10-5 mol dm-3
0.100 ± 8.40 mol dm -3 (3sf)

The figures I used to calculate the errors from I obtained from the British Standard maximum permitted errors (tolerances) for volumetric glassware table from my chemistry laboratory. All of the glassware used is of grade B standard.