Question

how is the initial rate of the reaction measured in this experiment?
select one:
○ by finding the slope of the steepest part of the pressure vs. time graph.
○ by measuring the time it takes for all the h₂o₂ to be consumed.
○ by observing how quickly the solution changes color.
○ by measuring the final temperature of the solution.

Explanation:

The initial rate of a reaction is related to the change in concentration (or a property related to concentration, like pressure for a gas - phase reaction) over a very short time interval at the start of the reaction.

• For a pressure vs. time graph, the slope of the graph represents the rate of change of pressure with respect to time. The steepest part of the pressure vs. time graph at the beginning of the reaction (when the reactant concentration is highest) gives the initial rate of the reaction.
• Measuring the time it takes for all the \(H_2O_2\) to be consumed (\(t_{total}\)) gives an average rate over the entire reaction, not the initial rate.
• Observing how quickly the solution changes color can be a way to measure the rate for some reactions (if there is a colored reactant or product), but it is not a general or direct method for measuring the initial rate in the context of a pressure - related experiment.
• Measuring the final temperature of the solution is related to the heat change of the reaction (a thermodynamic property) and not the rate (a kinetic property).

Answer:

By finding the slope of the steepest part of the pressure vs. time graph.