Question

Take Away 1 Find the concentration of the sample with Abs 0.675 Absorbance Concentration (mg/m) 0.0 0.000 0.5 0.161 2 lf the sample was diluted by adding 5ml of the sample to 30ml of water, calculate the concentration of the sample? 2.5 0.332 4.0 0493 5.0 0 656 0806 7.5 8.5 .191 1.554 12.0 3 Explain the term out of range

Answer 1

1)

According to Beer-Lambert law:

Absorbance ConcentratioT

46sorbance contant Concentration

0.675 absorbance lies between concentration 5 mg/mL and 7.5 mg/mL

Let C be concentration at 0.675 absorbance.

For this constraint:

0.675-0.656 06-0.65t

$\frac{0.15}{2.5}= \frac{0.019}{C-5}$

2.5mg/ml * 0.019 = 0.3167mg/mL (C-5)mg/mL

C (5 0.3167)mg/mL 5.3167mg/mI

0.675 absorbance corresponds to 5.3167 mg/mL.

2)

5 mL of this sample was obtained.

Mass of solute in the sample solution = concentration * volume

= 5.3167 mg/mL * 5 mL

= 26.5833 mg

Volume of diluted sample = 30 mL

Concentration of diluted sample = Mass of solute from sample / Volume of diluted sample

= 26.5833 mg / 30 mL

= 0.886 mg/mL

3) A reference range has upper and lower limit values for a corresponding to a given lab test within which the values are acceptable. An onservation falling too far from this range is high probability of error in the test,

Graph: Absorbance Vs. Concentration

0:5 10 4

According to Beer-Lambert law, the line drawn shows the linear variation of absorbance with concentration.

All the observations in the test lying near the line can be considered within range except the reading of 7.5 mg/mL which is too far from the straight line can be considered out of range