Question

Question 4 of 4 > Atomic emission spectroscopy and the method of standard addition are used to determine the Nat concentration and its uncertainty in an unknown sample. Increasing amounts of a 1.75 pg/mL standard Na' solution are added to a series of volumetric flasks containing 15.00 mL of the unknown solution. The volumetric flasks are then diluted to a final volume of 200.0 mL. Atomic emission spectroscopy is then used to measure the emission intensity of each solution Final volume (mL) 200.0 Unknown volume (ml) 15.00 15.00 15.00 15.00 15.00 Standard volume (mL) 0.00 5.00 10.00 15.00 20.00 200.0 200.0 200.0 200.0 Emission intensity 347.0 490.0 638.0 803.0 944.0 Based on the data in the table, determine the original concentration of Na' and its uncertainty in the unknown sample. Report the uncertainty with three significant figures. g/ml. + Mg/ml concentration:

Answer 1

(3) Solution : Given: Initial concentration of standard. Lid... = 10.2 mm Volume of standard. Ved = 1.00 mL Volume of serum. Verum = 9.00 mL Total volume, Viatal = Vad + Verum = 1.00 mL +9.00 mL = 10.00 mL After mixing. *Vse 10.2mMx1.00 mL-10 Final concentration of standard, Lid = 1.02mM Jinal Vega 10.00 mL Assume: Initial concentration of serum = [Literum Julitan Final concentration of serum, Lidl - Livez Leica Vives - Live Latin *9.00mL . 10.00ml = 0.900[List total Intensity of standard. Id = 414 Intensity of both standard and serum, Isid+serm = 853 Use the below equation to find theinitial concentration of serum. [Lire st = h (Lize]en +[Lire).a) Substitute as follows. [Li-- ... -( *5* 1.02mM +0.00[Lie= ...) [Live . - (* *1.02mm + **0900[-) [Line o * * 0.90[ Libros en esta « 1.02mM I Lie (49*~1.02 mm) [Licore at= 0.879mM