Angstroms. Using this information and the provided equations below, the molecular weight was calculated for each thickness. Using the calculated molecular weights, the best predictor of the curve was determined by performing error propagation with the values at each thickness. The error in concentration was calculated via error propagation with the curves of best fit of concentration vs. thickness. This error was then multiplied with the derivative of molecular weight relative to the concentration, which will help us calculate the error in molecular weights from the measured values.