27.50 + 27.30 + 27.70 = 27.50cm³ ± 0.10cm³
3
Data processing:
Standardization equation
H2NSO3H + NaOH H2NSO3Na + H2O
From the equation, we know that one mole of H2NSO3H reacted with one mole of HCL to form one mole of H2NSO3Na and one mole of H2O
Mole of HCL used = MV
1000
= 27.50cm³ ± 0.3636% x 0.09677 M
1000
= 0.002661mole ± 0.3636%
Based on the equation, one mole of H2NSO3H reacted with one mole of HCL. Therefore, 0.00261mole of HCL reacted completely with 0.00261mole of H2NSO3H.
However, 0.00261 ± 0.3636% mole of HCL reacted with only 25.00cm³ ± 1.00% of sodium carbonate. Therefore, the exact mole for sodium carbonate made in 250.00cm³ ± 0.060 % solution is 0.00261mole ± 0.3636% x 10 = 0.0261mole ± . (0.3636%+0.060% = 0.4236%)
Hence, to find the relative molecular mass:
Mole = Mass
RMM
0.02661mole ± 0.4236% = 2.5061g ± 0.004%
RMM
Therefore, the relative molecular mass for amidosulphuric is 94.18 ± 0.4276%.
Percentage error = |Experiment value – theoretical value| x 100%
Theoretical value
= |94.18-97.1| x 100%
97.1
= 3.007%
Conclusion: The relative molecular mass for sodium carbonate is 94.18. However, the theoretical value for sodium carbonate is actually 97.1. This difference in term of value is caused by a number of restrictions and limitations.
Evaluation: There are a number of limitations and error occurred during the experiments. These errors and limitation can cause differences between experimental value and theoretical value of the relative molecular value for sodium carbonate. Firstly, there is an error when determining the colour change of methyl orange. Theoretically, the colour of methyl orange will change from reddish pink to orange, but when the colour does change to orange, there will be different perception of what is actually orange. Some will consider certain colour is orange while some will not. Therefore, in order to overcome this problem, a controlled conical flask containing methyl orange which colour is orange should be put in front so that the students would know what exactly orange meant. Secondly, when the sodium carbonate is transfer from its container to the beaker to be saluted, some of the particles are not transferred. Instead, they remained in the container. Consequently, the molarities of sodium carbonate are not accurate. Therefore to overcome this error, the container should be wash with distilled water right after the acid is transferred into the beaker. The washing then, too, is transferred to the beaker.
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