IB Chemistry HL 2.2.13 Hl Arrhenius Factor a Questions

Use real HL exam questions to identify what the Arrhenius factor A represents and calculate it from the logarithmic intercept or supplied data.

Exam points

Identify the Arrhenius pre-exponential factor A as representing reactant nature and the frequency of collisions with suitable molecular orientation.
Distinguish A from activation energy Ea, gas constant R, temperature T and rate constant k in the Arrhenius equation.

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Study 2.2.13 (HL)—Arrhenius factor (A) conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

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The reaction between carbon monoxide, CO(g), and nitrogen dioxide, $\mathrm{NO}_{2}(\mathrm{~g})$ , was studied at different temperatures and a graph was plotted of $\ln k$ against $\frac{1}{T}$ . The equation of the line of best fit was found to be:

\ln k=-1.60 \times 10^{4}\left(\frac{1}{T}\right)+23.2

Figure for Question IB Chemistry HL 2.2.13 Hl Arrhenius Factor a Questions question 1 — IB Chemistry HL

Calculate the numerical value of A.

$\ln \mathrm{A}=23.2$ (intercept on y-axis);
$\mathrm{A}=1.190 imes 10^{10}$ ;

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IB Chemistry HL 2.2.13 Hl Arrhenius Factor a Questions question 1