Question

what is the purpose of performing run 4 at a lower temperature (approx. 10°c cooler) than runs 1 - 3?
select one:
to slow the reaction down to a safer speed.
to check if the gas pressure sensor works correctly at cold temperatures.
to prove that the catalyst only works at room temperature.
to collect data at a different temperature in order to calculate the activation energy (ea).

Explanation:

In chemical kinetics, the Arrhenius equation \(k = A e^{-\frac{E_a}{RT}}\) relates the rate constant \(k\) to the activation energy \(E_a\), temperature \(T\), and other constants. To calculate the activation energy \(E_a\), one needs rate - constant data at different temperatures. Performing an experiment (Run 4) at a lower temperature (compared to Runs 1 - 3) allows for collecting data at an additional temperature point. This additional data point, when combined with data from other runs (at different temperatures), can be used in calculations (such as using the Arrhenius equation in its linearized form \(\ln k=-\frac{E_a}{R}\times\frac{1}{T}+\ln A\)) to determine the activation energy.

Answer:

To collect data at a different temperature in order to calculate the activation energy (\(E_a\)).