# Transmittance of a solution? Question 3 only

Apr 25, 2017

a) $A = 0.118$
b) $a = 0.98 \text{ L } m o {l}^{- 1} c {m}^{- 1}$
c) $c = 7.9 \cdot {10}^{- 6} M$

#### Explanation:

3.a) Use the formula:
A = 2 - log_10(%T)
Note: A is the absorbance and %T is the percent of transmittance.
$A = 2 - {\log}_{10} \left(76.2\right)$
$A = 0.118045029$

$A = 0.118$

b) Use the formula:
$A = a b c$
Note: A is absorbance, a is molar absorptivity, b is path length, and c is concentration.

$0.118 = a \cdot 1.5 c m \cdot 0.0802 M$

$a = 0.981255434 \text{ L } m o {l}^{- 1} c {m}^{- 1}$

$a = 0.98 \text{ L } m o {l}^{- 1} c {m}^{- 1}$

c) $c = \frac{A}{a b}$

$c = \frac{0.118}{\left(10000 \frac{L}{m o l \cdot c m}\right) \left(1.5 c m\right)}$

$c = 0.00000787 M$

$c = 7.9 \cdot {10}^{- 6} M$