Question

1. A determination of silver in waste water was done with a method involving spling silver into the sample. A sample originally containing no silver was run six times with the following protocol. Each 100.0 mL sample was spiked with 200 g of silver and mixed well. From each of these prepared samples, a 5.00 mL aliquot was digested and the following results were obtained ug Ag found: 9.8, 9.2.9.3,9.5, 10.1, 8.9, 96, 9.4 a. What is the theoretical recovery value for silver in this experiment? (8 pts) b. Determine the mean and the relative standard deviation for this analysis. (You may use a spreadsheet or graphing calculator). (6 pts) C. Does this method recover the silver at a 95% confidence limit? Provide a calculation to support your answer. (8 pts)

a, b, and c please

Answer 1

a.

100 mL original sample was spiked with : 200 ug silver

5 mL aliquots it were digested :

thus, theoretical recovery value of silver :   (5 mL/ 100 mL )* 200 ug = 10 ug

b.

Sum, Σx:	75.8
Mean, x̄:	9.475 ug
Variance, s2:	0.13643

Steps

s2 =	Σ(xi - x̄)2 N - 1
=	0.955 7
=	0.13643

s =	√0.13643
=	0.37 ug

% RSD = S.D./mean *100 = 3.9 %