In the equation, I₀ sets the model’s starting brightness, while k controls how rapidly intensity falls as time increases. A larger k produces a steeper decline and a smaller predicted intensity at the same elapsed time. Interpreting these parameters separately helps students connect the graph’s shape to the modeled reaction behavior rather than treating the curve as an unexplained pattern.
Taking the natural logarithm of both sides gives ln I(t) = ln I₀ - kt. This converts the exponential relationship into a linear one, with ln I as the response and time as the predictor. A fitted line can therefore provide an intercept related to initial intensity and a slope related to decay rate.
Temperature is represented indirectly through k rather than by changing the equation’s basic form. If temperature changes reaction rate, the fitted decay constant can differ between glow sticks or trials. Comparing k values provides a mathematical way to quantify how conditions affect fading, while keeping initial intensity and elapsed time conceptually separate.
To apply the model, collect intensity values at recorded times, identify or estimate I₀, and fit the observations to the exponential expression. The resulting parameters can then be used to calculate intensity at another time. Organizing measurements by condition also allows separate curves and parameter values to be compared.
At a chosen elapsed time, substitute t into the fitted expression to estimate brightness. The same calculation can compare two conditions by evaluating their predicted intensities or decay constants. This makes the model useful for quantitative questions such as which sample fades faster and how much intensity remains after a specified interval.
An ideal exponential curve provides a concise approximation, but actual chemiluminescent behavior may not follow it perfectly. Comparing measured points with model predictions helps reveal the quality of the fit and whether the equation captures the observed fading pattern. This evaluation keeps the mathematical model connected to, rather than identical with, the physical process.