Substance X has a molar extinction coefficient (E) of 4725 l.mol-1. How many moles of X are needed to produce an absorbance of 1.0 in a 1 ml cuvette?
To find the number of moles of Substance X needed to produce an absorbance of 1.0 in a 1 ml cuvette, we can use the formula:
Absorbance (A) = E x c x l
Where:
A is the absorbance
E is the molar extinction coefficient
c is the concentration in moles per liter (M)
l is the path length of the cuvette in centimeters
In this case, we are given the absorbance (A) as 1.0, the molar extinction coefficient (E) as 4725 L·mol-1, and the path length (l) as 1 cm.
Rearranging the formula, we can solve for c:
c = A / (E x l)
Now we can substitute the given values:
c = 1.0 / (4725 L·mol-1 x 1 cm)
Note: 1 L = 1000 ml
To convert the concentration from L to ml, we divide the concentration by 1000:
c = 1.0 / (4725 ml·mol-1 x 1 cm)
c = 1.0 / 4725 ml·cm·mol-1
Therefore, the concentration in moles per ml (M) is approximately 0.000211 M.
Since we are working with a 1 ml cuvette, the number of moles (n) of Substance X needed to produce an absorbance of 1.0 is given by:
n = c x V
Where:
c is the concentration in moles per ml (M)
V is the volume in ml
Substituting the values:
n = 0.000211 M x 1 ml
n ≈ 0.000211 moles
Thus, approximately 0.000211 moles of Substance X are needed to produce an absorbance of 1.0 in a 1 ml cuvette.