Question

given the standard curve below, what is the concentration of a sample with an absorbance of 0.05? y = 0.002x + 0.0218 r² = 0.9961 absorbance 0.25 0.2 0.15 0.1 0.05 0 0 20 40 60 80 100 concentration (μg/l) 5 μg/l 37 μg/l 65 μg/l 100 μg/l

Explanation:

Step1: Identify the linear - equation

The equation of the line is $y = 0.002x+0.0218$, where $y$ is the absorbance and $x$ is the concentration.

Step2: Substitute the given absorbance value

We are given $y = 0.09$. Substitute $y$ into the equation: $0.09=0.002x + 0.0218$.

Step3: Solve for $x$

First, subtract $0.0218$ from both sides: $0.09−0.0218 = 0.002x$. So, $0.0682=0.002x$. Then, divide both sides by $0.002$: $x=\frac{0.0682}{0.002}=34.1\ \mu g/l$. The closest value among the options is $37\ \mu g/l$.

Answer:

37 μg/l