Nitric oxide reacting with chlorine, 2NO + Cl2 giving 2NOCl, appears to occur as an elementary termolecular step. What rate law follows from that step?
Arate = k[NO]^2[Cl2]
Brate = k[NO][Cl2]
Crate = k[NO][Cl2]^2
Drate = k[NO]^2[Cl2]^2
Answer & Solution
Correct answer: A. rate = k[NO]^2[Cl2]
1. For an elementary reaction, and only for one, the rate law follows straight from the coefficients.
2. The step consumes two NO and one Cl2 in a single three body collision.
3. So NO enters squared and Cl2 enters to the first power: rate = k[NO]^2[Cl2].
4. The overall order is 3, matching the three colliding particles.
5. The option k[NO][Cl2] forgets that two NO molecules must both be present in the collision.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 12 "Kinetics", section 12.6 Reaction Mechanisms_
Related questions
What forms when a substrate binds at an enzyme's active site during catalysis?Which enzyme model pictures the active site as flexible, changing shape to bind its substrWhich metal catalyses the hydrogenation of polyunsaturated fats and oils into saturated onHeterogeneous catalysis proceeds through at least four steps. Which comes first?Above 225 degrees Celsius, NO2 + CO giving NO + CO2 follows rate = k[NO2][CO]. With what kA reaction diagram shows a forward activation energy Ea and an enthalpy change delta H. WhIn the Arrhenius equation k = Ae^(-Ea/RT), what does the exponential factor represent?When carbon monoxide collides with an oxygen molecule, which collision orientation is more