1. The problem is to understand and use the formula for the rate of change of absorbance per minute, given by $$\frac{\Delta A}{\text{min}} = \frac{(\text{Abs}_{\text{sample}} - \text{Abs}_{\text{control}})}{t \text{ (min)}}$$ 2. This formula calculates the difference in absorbance between a sample and a control, divided by the time in minutes over which the change occurs. 3. Important rules: - Absorbance values (Abs) are unitless but must be measured under the same conditions. - Time $t$ must be in minutes to keep units consistent. 4. To use the formula, subtract the control absorbance from the sample absorbance to find the change in absorbance. 5. Then divide this difference by the time $t$ in minutes to find the rate of change per minute. 6. Example: If $\text{Abs}_{\text{sample}} = 0.8$, $\text{Abs}_{\text{control}} = 0.3$, and $t = 5$ minutes, $$\frac{\Delta A}{\text{min}} = \frac{0.8 - 0.3}{5} = \frac{0.5}{5} = 0.1$$ 7. This means the absorbance increases by 0.1 units per minute.