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Independent Variable:Mass weighed out of each unknown three samples
Speed of titration of each sampleNumber of moles used of MgSO4 in each unknown sampleDependent Variable:Volume of EDTA used for titrationDifferent color shades produced as the endpoint approachedPercentages of MgSO4in each unknown sampleControl:Concentration of EDTADrop of Eriochrom black T indicatorVolume of buffer solutionProcedure:Qualitative observations:Purple-blue color as the titration is complete
Strong odor from buffer solutionEriochrome Black T indicator colorQuantitative Observations:Mass of unknown sample= mass of weighing paper- mass of weighing paper with unknownTrial 1: 0.3933g-0.2458g=0.1475gTrial 2: 0.3887g-0.2456g=0.1431gTrial 3:0.3919g-0.2460g=0.1459gVolume of EDTA used: Vol. of initial EDTA – Vol. of final EDTATrial 1: 50ml-41ml=9mlTrial 2: 41ml- 32ml=9mlTrial 3: 32ml-23.2ml= 8.8ml# of moles of EDTA used= Volume of EDTA in liters*concentration of standardized EDTATrial 1: 9ml/1000= 0.009L*0.0459=4.131x E-4molesTrial 2: 9ml/1000= 0.009L*0.0459=4.131x E-4molesTrial 3: 8.8ml/1000= 0.0088L*0.0459=4.039xE-4moles# of moles of MgSO4 in Erlenmeyer flask: # of moles of EDTA/1Trial 1: 4.131x E-4moles /1= 4.131x E-4molesTrial 2: 4.131x E-4moles /1= 4.131x E-4molesTrial 3: 4.039xE-4moles/1=4.039xE-4molesMass of MgSO4 in the flask: # of moles of MgSO4in flask X molecular mass of MgSO4Trial 1: 4.131x E-4moles x 120.366g/mol= 0.04972gTrial 2: 4.131x E-4moles x 120.366g/mol= 0.04972gTrial 3: 4.039xE-4x 120.366g/mol=0.04862g% MgSO4 in the unknown sample: X 100
Trial 1:X 100= 33.71%Trial 2:X 100= 34.74%Trial 3: X 100= 33.32%Average % MgSO4in unknown = 33.92%Standard deviation: = 0.7337Graph,Tables: Unknown:49Concentration of the Standardized EDTA solution: 0.0459Trial Trial 2Trial 3Mass of weighing paper0.2458g0.2456g0.2460gMass of paper and unknown0.3933g0.3887g0.3919g