A solution containing 10-5 M ATP has a transmission %70 at 260 nm in a 1 cm cuvette.
Calculate the absorbance of the solution and molar absorptivity coefficient of ATP.
Absorbance = A = log (100/%T) = ?
A = ebc
A = absorbance
e = molar absorptivity = ?
b = 1 cm
c = 1E-5 M
Post your work if you get stuck.
To calculate the absorbance of the solution, you can use the equation:
A = -log(T)
Where A represents the absorbance and T represents the transmission percentage.
Given that the transmission is 70%, we can substitute this value into the equation:
A = -log(0.70)
Using a calculator to evaluate this expression, you will find that:
A ≈ 0.155
Therefore, the absorbance of the solution is approximately 0.155.
Next, the molar absorptivity coefficient (ε) can be calculated using the Beer-Lambert Law equation:
A = ε·c·l
Where A is the absorbance, ε is the molar absorptivity coefficient, c is the concentration of the solution, and l is the path length (in this case, 1 cm).
Rearranging the equation to isolate ε, we get:
ε = A / (c·l)
Substituting the given values, we have:
ε = 0.155 / (10^(-5) M · 1 cm)
Evaluating this expression:
ε ≈ 15500 M^(-1) cm^(-1)
Therefore, the molar absorptivity coefficient of ATP is approximately 15500 M^(-1) cm^(-1).
To calculate the absorbance of the solution, you can use the following formula:
Absorbance (A) = -log10(Transmittance/100)
In this case, the transmittance is given as 70%, so we can substitute this value into the formula:
A = -log10(70/100) = -log10(0.70)
Next, we can calculate the molar absorptivity coefficient (ε) of ATP using Beer-Lambert Law:
A = ε * c * L
Where:
A is the absorbance,
ε (epsilon) is the molar absorptivity coefficient,
c is the concentration of the solution in mol/L,
L is the path length of the cuvette (1 cm in this case).
Rearranging the formula, we can solve for ε:
ε = A / (c * L)
Given that the concentration of the ATP solution is 10-5 M (which is equivalent to 1.0 x 10^(-5) M), and the path length is 1 cm, we can calculate the molar absorptivity coefficient:
ε = (A) / (c * L) = ( -log10(0.70) ) / ( (1.0 x 10^(-5) M) * (1 cm) )
To determine the exact value, you can plug in these numbers into a calculator or use a mathematical software.