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25.00 mL of serum was pipetted into each of five 50 mL volumetric flasks. Varying additions of 2.934 M NaCl standard were made and the total volumes made up to 50 mL. The samples were analysed by sodium emission spectroscopy. Flask Volume of standard (ml) Na emission signal (mv) 3.13 1.000 5.40 2.000 7.89 3.000 10.30 4.000 12.48 600 Determine the concentration of sodium in the sample. Unit of concentration is M, but please do not type this in. Answer:

Answer 1

Here in addition to sample analyle Cunknown Standard analyre (known concentration) is added. So the response Cre signal) is due to both sample analyre and standard analyre. Here different volumes of standand added to sample Signal, s a concentration of analyre (cal. AzSz Kla Signal Absorbence Cervent voltage N = K[X] + [5]p] LXJf a concentration of unknown analyle in final Solution (x(i) = inerale nolume han ] | [X]F 2 [x] Xii) L a final volume of mixture _ YF CSJ a concentration of standard analyle in thal Solution 2 [ S Y here 7 m 2b VA 2) A z (vanable is k* (x,x + Kx[SO; 30 vs (volume a standard, initial) up Signal and Absorbante Y a mx the signalcon Absorbance CO) volkaos bance "S(1) slope, ma (S77) Innercept br k[x], xa) uf.

x-value (us) (signal) & values 3-13 J-40 1-000 7-89 2-000 _3-000 4-000 10-30 12.48. The ecuation of line & get s Y 0.423536% - 1-320517 o 42 4X1321 X 2 2-36x +3.12. b z [x), Vx (1) Coco x 3 x 25ML 2-934M. 312 ml 2 2 36 2) (x), 0.1gsm - cnat) 2 10-155) A San calulate extrapolation Cyou method can also).

standard addition methodt Signal, s s a 2 z concentration of analya) K.Ca som 2 final conceshatim of If a To a final concenharian of Stondave analyse VX X JY - standard analyte & k. ( x (x + vs CD, xa VS (1) > volume of sample mind, volume of standard respectively. The graph is by taking signal values on y-axis and volume of Standard Cus on x-axls. 67 In night side, the only variable in all Flasks is voot and remaining all are constant write above equation in form of y a mx to - sa k[s), v k W , ve Slopem y-intercept b ՎԻՏ Տ the reading of emission of anotyle when Extrapolating to x-axis 720 gives the line so that you so (volve how concentration v of analyle (comesponds to vso) en sample bolen