Question

25.00 mL of serum was pipetted into each of five 50 mL volumetric flasks. Varying additions of 2.923 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 Determine the concentration of sodium in the sample. Unit of concentration is M, but please do not type this in.

Answer 1

Concentration of sodium in sample = 0.078 M

Explanation

When Na emission signal values are plotted against Na concentration values, we get a straight line with equation : y = 40.455x - 0.025

Given : emission signal of sample = 3.13 = y

From the equation of line, x = (y + 0.025) / 40.455

x = (3.13 + 0.025) / 40.455

x = (3.155) / 40.455

x = 0.0780 M