1. Colorimetry and Beer’s Law
What is a calibration curve?

2. Colorimetry The color of an object is the color it REFLECTS!
It will absorb a complimentary color. This can vary based on the chemical.

3. Beer’s Law Relates concentration to absorption of light.
More molecules means
more absorptions.
More molecules indicates
more concentration.

4. Beer’s Law (cont’d) A = alc
Absorbance = constant * length * concentration
Increased concentration
means more absorbance.

5. Calibration Curve
Since A = alc is of form y = mx + b, we can graph A on y-axis and c on x-axis to get a line.
The line will allow us to calculate any concentration for any absorbance.

6. Calibration Curve (cont’d)
Take KNOWN concentrations and find their absorbances.
Use these to find the equation that will give any concentration for any absorbance.

7. Calibration Curve (cont’d)
y = 1.02x
But y = A and x = c
So:
A = 1.02c
What is concentration when A = 0.22?

8. Our Lab Procedures
Create known concentrations called standard solutions.
Use them to create a calibration curve.
Use calibration curve to find concentrations of unknown solutions.