Question

what can you do to determine the order of the phenolphthalein reaction with naoh? (select all that are correct)
plot 1/absorbance vs. time
plot the ln absorbance vs. time
plot the aborbance vs. time
nothing, you can tell the order from looking at the graph generated by the labquest

Explanation:

Step1: Recall reaction - order determination

For a reaction, the order can be determined by plotting different functions of concentration (or a quantity proportional to concentration like absorbance) against time. For a first - order reaction, plotting $\ln(A)$ (where $A$ is absorbance) vs. time gives a straight line. For a second - order reaction, plotting $\frac{1}{A}$ vs. time gives a straight line. And for a zero - order reaction, plotting $A$ vs. time gives a straight line. Just looking at a graph from LabQuest without proper analysis does not determine the order.

Step2: Analyze each option

• Plotting $\frac{1}{A}$ vs. time can help determine if the reaction is second - order.
• Plotting $\ln(A)$ vs. time can help determine if the reaction is first - order.
• Plotting $A$ vs. time can help determine if the reaction is zero - order.
• Just looking at the LabQuest graph is not sufficient for determining the order.

Answer:

plot 1/absorbance vs. time, plot the ln absorbance vs. time, plot the absorbance vs. time