attempt, she realizes that, to make the measurement, she must first dilute the sample solution. Julie transfers 1.3 mL1.3 mL of the sample to a 250 mL250 mL volumetric flask and fills the rest of the flask with water to the 250 mL250 mL line. She then uses the spectrophotometer to measure the concentration of the dilute solution as 5.5×10−5 M.5.5×10−5 M.

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Before investigating the scene, the technician must dilute the luminol solution to a concentration of 5.00 x 10-2 M. The diluted solution is then placed in a spray bottle for application on the desired surfaces. How many moles of luminol are present in 2.00 L of the diluted spray? Express your answer with the appropriate units.

What is the absolute uncertainty and relative uncertainty of the molarity of the solution?   M =  = 0.078376462 = 0.078 M Pb2+

1

Ben ran through the experiment and found the best-fit line listed below for his standard calibration curve of absorbance vs concentration in M. y = 3214.0x + 0.0076   Ben then prepared a solution that had 5.00 mL 0.002 M iron(III) nitrate in 1 M nitric acid, 3.00 mL 0.002 M potassium thiocyanate, and 2.00 mL DI water. If the absorbance for the solution was 0.436, calculate the equilibrium concentration of iron(III) thiocyanate in the solution. Report your answer in mM with three places after the decimal.

The standard solution is prepared by dissolving a known mass of zinc pellets with conc. HCl. The solution is then neutralized, transferred into a 250 mL volumetric flask and filled to the calibration mark. If 0.9809 g of Zn was weighed using an electronic balance with a relative uncertainty of ± 0.01 % and the 250 mL volumetric flask has a known relative uncertainty of ± 0.06 %, what would be the absolute uncertainty of the concentration of the solution? The molecular weight of the zinc pellets is 65.39 g/mol

A forensic chemist prepares a standard of caffeine in chloroform for use in a quantitative assay. The caffeine is purchased from a reputable supply company and arrives with a certificate stating that it is 99.5% pure or better (written 99.5% + or + 99.5%). The analyst needs to make a stock solution at a concentration near 1 mg/mL. To do so, she obtains a Class A 50.00 mL volumetric flask (± 0.05 mL) and uses an analytical balance to accurately weight out 49.6 mg. The balance uncertainty is listed as ± 0.0003 g near the 50 mg range. The analyst quantitatively transfers the powder to the flask and carefully dilutes the solution to volume. Report the concentration of the solution in mg/mL and the propagated uncertainty associated with it. Use the NUSAP form to report your answer with the proper number of significant figures in the final result. You get to pick which “assessment” is presented.

The following volumes of 0.000300 M SCN are diluted to 15.00 mL. Determine the concentration of SCN in each sample after dilution. These values will be used during the experiment. To enter exponential values, use the format 1.0e-5. Sample 0.000300 M SCN (mL) [SCN'] (M) 1 1.50 3.50 7.00 4 10.00 3.

3-3 Types of Error; 3-4 Propagation of Uncertainty from Random Error ¹. If A = 3.475 (±0.002), B = 87.336 (±0.001), C = 10.004 5 (±0.000 5), D = 11.8 (±0.2), and E = 5.10 (±0.03), report the answers of the following calculations with both the absolute uncertainty and the percent relative uncertainty. a) (A - B) X E c) (10-) / (E/1000) b) (C+D)/(A X E) d) [ (A + B + C) x (B - C - E)] / [DXE]