Cobalt was used as an internal standard to analyze a sample of titanium with ato
ID: 979802 • Letter: C
Question
Cobalt was used as an internal standard to analyze a sample of titanium with atomic absorption spectroscopy. A mixture was prepared by combining a 5.00 mL Ti solution of unknown concentration with 3.50 mL of a 10.5 mu g/mL solution of Co. The atomic absorbances were measured as 0.126 and 0.230 for Ti and Co, respectively. As a reference, a standard mixture containing2.46 mu g Co/mL and 2.16 mu g Ti/mL was prepared and measured to have a signal-to-signal radio of 2.91 Ti:1.00 Co. Determine the concentration (moles/L) of titanium in the original unknown solution.Explanation / Answer
3.50 ml of 10.5 ug/ml of Co has AAS value of 0.230 for Co
Unknown : 1.50 ml of x ug/ml of Ti has AAS value of 0.126 for Ti
standard,
2.46 ug Co/ml has AAS value of 1.00 (ratio)
2.16 ug Ti/ml has AAS value of 2.91 (ratio)
For Co = 10.5 x 1/2.46 = 4.27
Ti in the unknown = 4.27 x 2.91 = 12.42 ug/ml
concentration of Ti in the original solution = 0.1242/47.87 = 2.60 x 10^-6 mols x 3.33/0.005 = 0.002 M