Question

2. (2 points) In the determination of calcium in antacid tablets by atomic absorption, a 0.5133 g sample was dissolved and diluted to 1000. mL. Three 5.00 mL aliquots were diluted to 50.0 mL each after addition of 0, 1.00, and 2.00 mL, respectively, of a calcium standard containing 0.500 mg Ca/mL. The absorbances of the three solutions were 0.310, 0.475, and 0.640, respectively Determine the mg Ca in the sample.

Answer 1

The difference in absorbance is proportional to the difference in concentration of standard.

07.01.2014 Stock Soluhcn A. .S133 of_Sample in_loooma Soluton 1 SmL of StoI boluhon tom of Stamdand Dilukd o 50 ml CancentrahaM of Stamdaad Solahian 2 Sm of Sts cic 6luh on + i mL of Skamdand Dilu ted So mL Cncentvahan of Stamdand in solution2 X \ ML O.Smna SOME 0.01Mg/m of Stack doluhn t2mL of Skamdland Soluhn 3 S m DIluted to SO mi Standand in Soluan3 Concemkaha Of O-SmghmLXm 5ormt O-02M mL 5h additve Abaax hamce AC because ad1 ane A = E C CanMant - AbAovban ce A, : f Saluhn abror bamie of Salubn2 and 3 Yefectvely AAg

Ag-A O640 0475 0.165 Ci, amd 3. COMcemNahom of Solukami, 2 amd 3 xedteckuely. '. Coe cam Aay that of stamdand Saluhan 9ives absox bamie ofO.16S The abdovbamie Solukan A ig givem as 0.310 covreafonding the ConcenN ahon of ca O-01mglmL XO.310 O-165 Amout Co in SmL of StocC doluhian O O1818 mA tmL XSamL Concentahon of Sock soluhan .939 mg AmOut Ca o-1818 3 (oR) 181-8 mI. The Samle contaiw 187-8 mof O 014 AADCH 2014