DATA PROCESSING
Percentage of Uncertainties
Mass of amidosulphuric acid
0.0001 x 100% = 0.004%
2.5001
Amidosulphuric acid in volumetric flask
0.25 x 100% = 0.1 %
250.00
Amidosulphuric acid in pipette
0.03 x 100% = 0.12 %
25.00
Sodium hydroxide used
0.10 x 100% = 0.4%
25.03
Average Volume of Sodium Hydroxide used
=25.10cm³+25.10cm³+25.20cm³
3
= 25.03cm³
Standardization equation
H2NSO3H + NaOH H2NSO3Na + H2O
From the equation we can see that 1 mole of amidosulphuric acid (H2NSO3H) reated with 1 mole of sodium hydroxide (NaOH) to form one mole of H2NSO3Na and one mole of water (H2O).
Number of mole, n for sodium hydroxide
n = MV
1000
= 0.096M x 25.03cm³
1000
= 0.0024 mole ± 0.4%
From the equation,1 mole of sodium hydroxide reacted with 1 mole of amidosulphuric acid.So, we can say that 0.0024 ± 0.4% mole of sodium hydroxide reacted with 0.0024± 0.4% mole of amidosulphuric acid in this reaction based on the ratio of mole in equation.
Number of mole of Amidosulphuric acid in volume of 250 cm³
The mole 0.0024± 0.4% mole of amidosulphuric acid is in the volume of 25.0 cm³ ± 0.12% after measured using pipette. The actual mole of amidosulphuric acid is in the volume of 250 cm³ ± 0.1% after its preparation in volumetric flask.
Mole : 0.0024 mol x 10 = 0.024 mol
Percentage of uncertainty :0.4% + 0.1% = 0.5%
Therefore,the number of mole of amidosulphuric acid in 250 cm³ is 0.024 mole ± 0.50%.
Determining relative Molecular Mass of amidosulphuric acid
Mole = Mass
RMM
0.024 mol = 2.5001
RMM
RMM = 2.5001
0.024
= 104.17
Percentage of uncertainties
= 0.5% + 0.004%
= 0.504%
Therefore, the RMM for amidosulphuric acid is 104.3 ± 0.5040%
Theoretical value for RMM of amidosulphuric acid
H2NSO3H
= 2(1.01)+14.01+32.06+3(16.00)+1.01
= 97.1
Percentage Error
Percentage error = |Experiment value – theoretical value| x 100%
Experiment value
= 104.3-97.1 x 100%
104.3
= 6.90%
CONCLUSION AND EVALUATION
Conclusion
The theoretical value for Relative Molecular Mass of amidosulphuric acid is 97.1 whereas experimental value of RMM that obtained from the experiment is 104.3.The percentage error is 6.90%. The difference of RMM between the theoretical and experimental value is due to limitations and errors that occurs throughout the experiment.
Evaluation
There are some errors and limitations occurred throughout the experiment that caused the experimental value to be different from the theoretical value. These errors have affected the final result of the experiment. Firstly, during the transferring process of amidosulphuric acid from the weighing boat into beaker. During the process, there are possibilities that not all amidosulphuric acid in the weighing boat is transfered into the beaker and some of the acid still left in it. So, the thing that we should do to overcome this is by pouring some distilled water into the container, and transfer the water back into beaker. The water will eventually bring left acid along into the beaker.
Secondly, during the dilution of solid amidosulphuric acid in distilled water in beaker. During the mixing using glass rod, there are possibilities that the acid did not dissolved completely in water. So, to overcome this, mix the acid harder in water to ensure complete dissolving of amidosulphuric acid in distilled water.
Lastly, when the titration reached its end-point , students facing problems to actually defined what is light pink. They tend to confuse to differentiate which is pink and which is purple to ensure that the titration had reached the end point or wether they have overshoot the sodium hydroxide into amidosulphuric acid solution. So, to overcome this, a beaker with amidosulphulric acid solution that has been titrated until it reached the end point with sodium hydroxide and has colour of pink should be prepared as controlling variable and indicator for the students.
by
naqiksah93 (student)
