Indicate whether each statement is true or false. (a) If you m...

Question

Indicate whether each statement is true or false. (a) If you measure the rate constant for a reaction at different temperatures, you can calculate the overall enthalpy change for the reaction.

Accepted Answer

Identify the relationship between the rate constant (k) and temperature, which is described by the Arrhenius equation: $ k = A e^{-\frac{E_a}{RT}} $, where $ A $ is the pre-exponential factor, $ E_a $ is the activation energy, $ R $ is the gas constant, and $ T $ is the temperature in Kelvin.. Understand that the enthalpy change ($ \Delta H $) of a reaction is different from the activation energy ($ E_a $). The activation energy is the energy barrier that must be overcome for reactants to transform into products, while the enthalpy change is the overall heat absorbed or released during the reaction.. Recognize that measuring the rate constant at different temperatures primarily provides information about the activation energy through the Arrhenius plot, where plotting $ ln(k) $ versus $ \frac{1}{T} $ gives a slope of $ -\frac{E_a}{R} $.. Conclude that while the activation energy can be derived from the temperature dependence of the rate constant, the overall enthalpy change of the reaction cannot be directly calculated from this data alone, as it requires additional thermodynamic information such as the heat capacities of reactants and products.. Determine the statement as false, since the rate constant measurements at different temperatures allow calculation of the activation energy, not the direct calculation of the overall enthalpy change of the reaction.

Indicate whether each statement is true or false. (a) If you measure the rate constant for a reaction at different temperatures, you can calculate the overall enthalpy change for the reaction.

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Key Concepts

Rate Constant and Temperature

Enthalpy Change (ΔH)

Van 't Hoff Equation