Respuesta :
Answer:
a) [tex]9.7532\times 10^{-5} M[/tex] is the concentration of the compound in the cuvette.
b) 0.02438 M is the concentration of the solution in the 10-mL flask.
c) 63.57 milligrams of compound were used to make the 10-mL solution.
Explanation:
Using Beer-Lambert's law :
Formula used :
[tex]A=\epsilon \times c\times l[/tex]
where,
A = absorbance of solution
c = concentration of solution =
a) We have :
[tex]\epsilon =5793 M^{-1} cm^{-1}[/tex]
l = path length = 1.000 cm
A = 0.565 , c = ?
[tex]0.565=5793 M^{-1} cm^{-1}\times c\times 1.000 cm[/tex]
[tex]c=9.7532\times 10^{-5} M[/tex]
[tex]9.7532\times 10^{-5} M[/tex] is the concentration of the compound in the cuvette.
b) The initial concentration of solution in 1 mL = [tex]C_1[/tex]
[tex]V_1=1 mL[/tex]
Final concentration of solution after dilution = [tex]C_2=9.7532\times 10^{-5} M[/tex]
[tex]V_2=25 mL[/tex]
[tex]C_1V_1=C_2V_2[/tex]
[tex]C_1=\frac{C_2V_2}{V_1}=\frac{9.7532\times 10^{-5} M\times 25 mL}{1 mL}[/tex]
[tex]C_1=0.002438 M[/tex]
Concentration of 1 mL solution = 0.002438 M
Then concentration of the 10 mL solution :
[tex]10 mL\times 0.002438 M = 0.02438 M[/tex]
0.02438 M is the concentration of the compound in the 10-mL flask.
c) Amount of compound were used to make the 10-mL solution =m
Molarity of the solution = 0.02438 M
volume of the solution = 10 m L = 0.010 L
[tex]Molarity=\frac{Moles}{Volume(L)}[/tex]
[tex]0.02438 M=\frac{Moles}{0.010 L}[/tex]
Moles of compound:
0.02438 M × 0.010 L= 0.0002438 mol
Mass of 0.0002438 mol unknown compound =
0.0002438 mol × 260.73 g/mol = 0.06357 g
0.06357 g = 63.57 mg (1 g = 1000 mg)
63.57 milligrams of compound were used to make the 10-mL solution.
