Using a graphing calculator to determine a first-order rate constant when the infinity reading is unknown

The infinity value is an important aspect of first-order reactions that is often neglected. In fact, incorrect or missing infinity values can produce curvature of the logarithmic plot which can lead to incorrect assumptions that a reaction is not first-order. This paper uses data from the classic acid–catalyzed sucrose inversion experiment to demonstrate how to use a graphing calculator as an alternate means to determine the infinity value of the physical property being used to follow the progress of a chemical reaction and how to determine the rate constant which governs a first-order reaction when the infinity value is unknown.