Answer:
The value is [tex]C = 21.07 ppm[/tex]
Explanation:
From the question we are told that
The volume of the first aliquot is [tex]V_a1 = 25.0 \ mL[/tex]
The volume after dilution is [tex]V_A = 50.0mL[/tex]
The Absorbance of the first solution is [tex]A_1 = 0.656[/tex]
The wavelength at which the absorbance occurred is [tex]\lambda _1 = 348 nm = 348*10^{-9} \ m[/tex]
The length of the cell [tex]l = 2.50 \ cm[/tex]
The volume the second aliquot is [tex]V_{a2} = 25.0 \ mL[/tex]
The volume of the solution it was mixed with is [tex]V_s = 10.00mL[/tex]
The concentration of quinine in the 10 mL solution [tex]Z = 25.7ppm[/tex]
The volume of the second solution after dilution is [tex]V_d = 50.0 mL[/tex]
The absorbance of the second solution is [tex]A_2 = 0.976[/tex]
Generally the concentration of quinine is mathematically represented as
[tex]C = \frac{A_1 *Z * V_s }{(A_2 -A_1) V_{a2}}[/tex]
=> [tex]C = \frac{ 0.656 * 25.7 * 10.0}{ (0.976 - 0.656) * 25}[/tex]
=> [tex]C = 21.07 ppm[/tex]
