An analyst is verifying the linear range for a new food-coloring dye
CHEMISTRY · Multi-part · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures
Problem
An analyst is verifying the linear range for a new food-coloring dye. Absorbances were collected for five standard solutions in a 1.00 cm cuvette.
Concentration (mM) | Absorbance
0.00 | 0.000
0.30 | 0.180
0.60 | 0.365
0.90 | 0.545
1.20 | 0.700
A beverage sample, analyzed under the same conditions, gives an absorbance of 0.390.
(a) Plot (conceptually) absorbance versus concentration for the standards and comment on whether a single straight line adequately describes all five data points.
(b) Identify the concentration range that satisfies the proportionality between absorbance and concentration, and justify the exclusion of any data points that deviate from this proportionality.
(c) Using only the data that satisfy the proportionality, determine the concentration of the dye in the beverage sample. Show calculations and clearly state any assumptions made about interpolation or extrapolation.