Answer to Question #65323 in Chemistry for Harleen

Question

For the following analytical scenario below which involved initially diluting 20 ml of the original water sample into a 1000 ml volumetric flask. Subsequently, the sample was prepared and analyzed as depicted below:


Volemetric flask (500ml) #1
Sample Composition: 5 ml of sample + 0 mL of 300 ppm Na 0.5% LiCl2
Absorbance: 0.12


Volemetric flask (500ml) #2
Sample Composition: 5 ml of sample + 1 ml of 300 ppm Na + 0.5% LiCl2
Absorbance: 0.17


Volemetric flask (500ml) #3
Sample Composition: 5 ml sample + 2 ml of 300 ppm Na + 0.5% LiCl2
Absorbance: 0.21


I. If all the flasks were diluted to a final volume of 500 ml with distilled water calculate the final concentration of sodium in the sample through a graphical and mathematical solution.

II. Why Lanthanum and Cesium or Lithium are added to solutions to be analysed for Calcium and Sodium respectively?