L7_CHEM480_JCCYu

# L7_CHEM480_JCCYu - Crime Lab Chemistry parts per...

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1 Crime Lab Chemistry parts per million (ppm) wt of a solute c ppm = ------------------- X 10 6 wt of solution The density of a diluted aqueous solution is close to 1.00 g/mL. We frequently equate 1 g of water with 1 mL of water. So you will also see something like: ppm = mg/kg = μ g/g = ng/ μ g. ppm = mg/L = μ g/mL = ng/ μ L A solution contains 12.6 ppm of dissolved Ca(NO 3 ) 2 (which dissociates into Ca 2+ and NO 3 - ). Find the concentration of NO 3 - in parts per million. parts per billion wt of a solute c ppb = ------------------- X 10 9 wt of solution ppb = μ g/kg = ng/g = pg/ μ g. ppb = μ g/L = ng/mL = pg/ μ L How about ppt? (parts per trillion) ppt= ng/L = pg/mL = fg/ μ L

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2 Convert ppb to Molarity ± 34 ppb of C 29 H 60 FW 408.8 in rainwater sample. Convert ppb into Molarity. ppb = μ g/L 34 b t i 34 f C H iL f 34 ppb contains 34 ug of C 29 60 in a L of sample. So. nM 83 M 10 8.3 g/mol 408.8 g/L 10 34 8 - -6 = × = × Ex. ± A diluted aqueous solution has a density near 1.00 g/mL. Suppose the solution contains 1 ppm of the solute. Express the concentration of solute in g/L, mg/L, μ g/mL, and μ g/L. 1ppm=1mg/L=1x10 3 g/L ± 1 ppm = 1 mg/L = 1 x 10 -3 ± 1 ppm = 1 μ g/mL = 1 x 10 3 μ g/L Quantitative Measurement ± Numerical quantity ± Appropriate units ± Uncertainty of the measurement ± Usually the smallest numerical value that can be estimated with the measuring device.
3 Uncertainty ± Absolute uncertainty : expresses the margin of uncertainty associated with a measurement.

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L7_CHEM480_JCCYu - Crime Lab Chemistry parts per...

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