Question

green dye experiment
determining concentration
the calibration curve is shown below, including the linear best fit line.
absorbance vs.concentration at 425 nm
y = 105x
what is the concentration of an unknown sample if the absorbance is 0.68?
71.4 m
0.0140 m
154 m
0.0065 m

Explanation:

Step1: Identify variables from equation

The calibration curve equation is $y = 105x$, where $y$ = absorbance, $x$ = concentration.

Step2: Substitute given absorbance

Set $y = 0.68$, so $0.68 = 105x$.

Step3: Solve for concentration $x$

Rearrange to solve for $x$: $x = \frac{0.68}{105}$
Calculate the value: $x \approx 0.006476 \approx 0.0065$

Answer:

0.0065 M (matches option: 0.0065 M)