SC CHEM 321 - Gravimetric Determination of Calcium (5 pages)

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Gravimetric Determination of Calcium



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Gravimetric Determination of Calcium

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Pages:
5
School:
University Of South Carolina-Columbia
Course:
Chem 321 - Quantitative Analysis
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Experiment 2 Gravimetric Determination of Calcium Chemistry 321L 02M Post Lab By Cameron Kahn 26 February 2014 TA Muditha Dias Kahn 1 P a g e Single Investigator Tasks 10 points each 1 Produce a flow chart depicting your sample handling 2 Tabulate all data Sample A Antacid tablet 1 000mg Mass sample 1 0078 g Mass of Mass of Mass crucibl crucibl product e g e plus g product g Crucible 1 32 44 32 86 0 42 Crucible 2 32 96 33 17 0 21 Crucible 3 24 58 24 70 0 12 Average Molarity of product mol L Mass g of Calcium in 5mL 0 00287 4 0 00143 7 0 00082 1 0 001711 0 115198 1 15198 4 0 05759 0 57599 9 2 0 03291 0 32913 4 8 0 68570 5 0 42225 2 114 3068 Molarity of product mol L Mass g of Calcium in 5mL Weight percent w w of Calcium in sample 0 00084 9 0 00068 4 0 00075 3 0 00076 2 0 034011 0 34011 Standard Deviation Sample B Tums 1 000mg mass sample 1 0055 g Mass of Mass of Mass crucibl crucibl product e g e plus g product g Crucible 1 33 07 33 19 0 124 Crucible 2 32 90 33 00 0 1 Crucible 3 32 49 32 60 0 11 Average Kahn 2 P a g e 0 02742 8 0 03017 1 Mass g of Calcium in 50mL Mass g of Calcium in 50mL 0 27428 2 0 30171 0 30536 7 Weight percent w w of Calcium in sample 57 1534 2 32 6590 9 68 0397 8 33 8249 3 27 2781 7 30 0059 8 30 3696 9 Standard Deviation Class Sample mean sd sd 2 Aantacid weight 68 1 61 3 65 7 21 1 33 5 1 79 55 4 112 4 0 726 2 05 1 8 37 3 10 2 2 34 33 8361 4 34 4916 5 1189 674 0 03306 6 Btums weight 27 3 69 3 37 3 42 2 44 6 2 87 12 17 6 2 34 2 87 20 5 6 22 2 07 22 09 21 0246 2 442 034 8 3 Explain how fundamental measurements show up in this lab and what piece of equipment is calibrated A fundamental measurement is not derived from another measurement In this lab fundamental measurements show up in processes such as measuring mass When measuring the mass of the precipitate we had to use a calibrated balance 4 Solve for the mean and 95 confidence interval for Ca content for your sample Do this for both a and b Do this for both molarity and weight percent The mean is the average The 95 interval z take the standard deviation for a and b multiply by table value at the 95 interval Kahn 3 P a g e Collective Tasks 20 points each 5 Use the pooled standard deviation technique to solve for the class mean and standard deviation for calcium in Brand A supplement and Brand B supplement Standard deviation 34 49 for Sample A 21 02 for Sample B Mean 33 83 for Sample A 22 09 for Sample B Spool Na 1 S a2 Nb 1 S b 2 Na Nb 2 13 1189 674 12 442 0348 28 82 25 6 Use the t test to determine if your Ca determination is different from the class pooled value at the 95 level of confidence for your brand Spool Sample A mean 33 83 Standard deviation 34 49 Sample B mean mean 22 09 Standard deviation 22 01 2 178 2 484 44 Spool 13 92 5 Class sample A mean 33 84 Standard deviation 34 49 Class sample B mean 22 09 Standard deviation 21 02 13 1189 674 12 442 0348 Spool 28 82 25 Texp X 1 X 2 S 12 S 22 where X1 and X2 are the means for my sample and class sample n n 1 n2 is the number of samples I used 3 because that s how many samples we had of each tablet and S1 and S2 are the standard deviations for my sample and class sample Kahn 4 P a g e Sample A Texp Sample B Texp 33 83 33 84 1189 56 1189 56 3 14 22 09 22 09 S 12 S 22 3 13 Degrees of freedom is 5 Ttable 2 015 No statistical difference 7 Use the t test to determine if the class can resolve from Brand A and Brand B at the 95 level of confidence Xa Xb Na Nb Spool Na Nb 33 83614 22 05 14 13 28 824 14 13 Ttable 2 179 Texp 1 0616 1 0616 2 179 therefore since our Texp was less than our Ttable value found at the 95 confidence level with 12 degrees of freedom then our hypothesis is supported that at the 95 confidence interval both brand A and B have statistically the same mass weight percent w w of calcium Kahn 5 P a g e


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