Determination of the concentration of sulphuric acid by titration Essay

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Determination of the concentration of sulphuric acid by titration

Aim
To determine the concentration of a solution of sulphuric acid by titration with sodium hydroxide

Apparatus
250mL E-flask, stirrer with magnet, burette +0.1 ml, 10.0ml pipette

Chemical
H2SO4(aq), 0.100M NaOH(aq), BTB (pH-indicator)

Experimental
The burette is rinsed by and filled up by NaOH-solution. It is required that no air bubbles present in the burette. 10.0ml of the H2SO4 is filled into the E-flask and diluted by distilled water to about 100 cm3. Then 10 drops of BTB and a magnetic stirring bar are added to it. After dropping 5 drops of   BTB, the H2SO4 starts to change colour to pale yellow. Furthur dropping 5 more drops, it becomes yellow. The E-flask is placed on the magnetic stirrer. The liquid is stirred. H2SO4 is titrated with NaOH. The H2SO4 is observed to have a drop of blue colour liquid when adding a drop of NaOH. However, it gradually disappear. The titration is considered to be end until the colour turns to green. Then the above procedure is repeated twice. The collected data is shown in table 1


Table 1. Raw data from titration of sulphuric acid with sodium hydroxide to determine the concentration of sulphuric acid
Trial 1 st (+0.1ml) 2nd (+0.1ml) 3rd (+0.1ml)
Vol. Of NaOH used when a blue drop starts to appear but gradually disappear 12.2 ml 11.7 ml 12 ml
Vol. Of NaOH used when the colour is green 20.0ml 19.3 ml 19.4 ml




Calculations
 The equation of titration: 2NaOH + H2SO4  2H2O + Na2SO4
 Average of volume of NaOH used for titration: (20.0+19.3+19.4)/3=19.57ml
 Amount of NaOH =   Concentration of NaOH
Volume of NaOH
Amount of NaOH =0.1
0.1957
Amount of NaOH =1.957 x 10-3 mol

 Molar ratio of NaOH and Na2SO4 :           2:1
NaOH =0.5 Na2SO4
 Amount of Na2SO4: 1.957 x 10-3 /2 =9.785x 10-4 mol
 Amount of Na2SO4   =   Concentration of Na2SO4
Volume of Na2SO4
 9.785x 10-4   =...

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Determination of the concentration of sulphuric acid by titration. Anti Essays. Retrieved July 26, 2014, from the World Wide Web: http://www.antiessays.com/free-essays/Determination-Of-The-Concentration-Of-Sulphuric-59202.html