A 179 mL solution of a copper complex with a molecular weight of 491.9 g mol-1 was made. The absorbance of the solution at 638 nm wavelength was 0.376 using a 1 cm cuvette. It is known that this copper complex has a molar absorptivity (extinction coefficient) of 324.4 M-1 cm-1 at this wavelength.What was the mass of the copper complex dissolved in the solution in mg? Report your answer to 3 significant figures.
A = ebc
A = 0.376
e = 324.4
b = 1 cm
c = unknown.
Solve for C in molarity.
mols = M x L where L = 0.179\
grams = molos x molar mass. Solve for grams and convert to mg.
is it 102 mg
rounded to 3 significant figures.
To find the mass of the copper complex dissolved in the solution, we need to use the Beer-Lambert law, which relates the absorbance of a solution to the concentration of the absorbing species present.
The Beer-Lambert law is given by the equation:
A = εcl
Where:
A is the absorbance,
ε is the molar absorptivity (extinction coefficient),
c is the concentration of the absorbing species, and
l is the path length of light through the solution.
Given values:
A = 0.376 (absorbance),
ε = 324.4 M-1 cm-1 (molar absorptivity), and
l = 1 cm (path length of light).
We can rearrange the equation to solve for the concentration (c):
c = A / (ε × l)
Substituting the given values:
c = 0.376 / (324.4 M-1 cm-1 × 1 cm)
c ≈ 0.001159 M
Now we have the concentration of the copper complex in moles per liter (M). To convert this to moles per milliliter (mmol/mL), we need to divide by 1000:
c = 0.001159 M / 1000
c ≈ 0.000001159 mol/mL
Finally, we can calculate the mass using the formula:
mass = (concentration × volume × molecular weight) / 1000
Given values:
concentration = 0.000001159 mol/mL,
volume = 179 mL, and
molecular weight = 491.9 g/mol.
mass = (0.000001159 mol/mL × 179 mL × 491.9 g/mol) / 1000
mass ≈ 0.1009 g
To report the answer in milligrams, we multiply by 1000:
mass ≈ 100.9 mg
Therefore, the mass of the copper complex dissolved in the solution is approximately 100.9 mg.