Test-exam 2

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Unformatted text preview: paste C(mg/L) Tap Water logC Tap Water C(mg/L) Linear Least Square Error Analysis: s sub r N Sxx y bar M Toothpaste -0.00924057 -0.086247 -2.12810374 -57.79302 95.62378 0.607751 4.052763 -0.5083 0.310241 0.491949 6 6.239574 44.8 1 Tap water -0.010338 -0.007387 -2.380898 ± 0.09 mg/L ±logC s sub c ±C, mg/L Rel error, % Toothpaste: C should be reported as determine what should be in D41? a. 0.087 b. 2.13 c. 4.05* 13 d. 20.1 e. 60.5 Ans. D41 = D25 Atomic Absorption and Emission Spectrometry 21. 1.00 10 2 ppm of Ca (AW=40.078g/mol) is how many moles per liter of CaCl2 (FW=110.984g/mol)? a. 4.01 10 4 b. 2.50 10 3 * c. 0.277 d. 2.50 e. 100. Ans. mgCa 1mmolCa 103 molCa 1molCaCl2 100 40.078mgCa 1mmolCa 1molCa L 22. When preparing the 100-mL 1000-ppmCa2+ standard working solution (SS), some in the class experienced difficulty in dissolving the CaCO3(s) (FW=100.087g/mol). This is because CaCO3(s) is insoluble in water; a certain amount of 6M HCl is needed. Suppose you weigh out 0.2512-g of dried CaCO3(s) to make the SS, wha...
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This note was uploaded on 03/03/2011 for the course CHEM 100A taught by Professor Dai during the Spring '06 term at UCSD.

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