Explain the effect of temperature on the rate of a reaction using the Arrhenius equation. Draw the Maxwell-Boltzmann distribution at two temperatures and show how Ea is found graphically.

1. 1 · State the fact and the law. A 10 K rise nearly doubles k. k = A e^(−Ea/RT); explain A, Ea, R and T.
2. 2 · Explain activation energy. Molecules must gain Ea to form the activated complex; e^(−Ea/RT) is the fraction of molecules with energy ≥ Ea.
3. 3 · Draw the distribution curves. Fraction of molecules vs kinetic energy at T and T + 10; mark Ea; shade the areas beyond Ea (about double at T + 10).
4. 4 · Show the graphical method. ln k = −Ea/RT + ln A. Plot ln k against 1/T: a straight line, slope = −Ea/R, so Ea = −slope × R.
5. 5 · Give the two-temperature form. log(k₂/k₁) = [Ea/(2.303R)] × [(T₂ − T₁)/(T₁T₂)].
6. 6 · Link to daily life. A pressure cooker cooks faster because the temperature inside is higher.
7. 7 · Close in one line. So temperature raises the rate by raising the fraction of effective, high-energy molecules, not by changing Ea.

Scoring tip: On the distribution graph, the T + 10 curve must be lower and wider, with its peak shifted right; shade beyond Ea on both.