alleryStart learning →Why are termolecular elementary steps uncommon?
AThree particles cannot form a single bond
BThree particles always give unstable products
CThree particle steps break the rate law rules
DThree particles rarely collide at the same instant
Answer & Solution
Correct answer: D. Three particles rarely collide at the same instant
1. A termolecular step needs three particles at the same place at the same instant.
2. That is less than one thousandth as likely as two particles meeting.
3. So such steps are rare, though a few are established, such as the ones in the reaction of nitric oxide with oxygen.
4. Nothing forbids three particle steps in principle, so the rule based options are wrong.
5. The barrier is one of probability, not of bonding.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 12 "Kinetics", section 12.6 Reaction Mechanisms_
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