All questions
AP Chemistry
5.11 Catalysis
5.6 Reaction Energy Profile
5.5 Collision Model
AdvancedMCQDrawing RepresentationsConceptual14.5k
A diagram with four horizontal panels labeled Stage 1, Stage 2, Stage 3, and Stage 4. A legend maps: small open circle = H atom, medium filled black circle = C atom, large gray hatched circle = Pt atom. In each panel, the bottom contains a catalyst slab of exactly 12 Pt atoms in two rows of 6. Stage 1 shows one separate H2 molecule (two bonded open circles) and one C2H4 molecule (two bonded black circles, each with two open circles) in the space above the slab. Stage 2 shows two dissociated open circles bonded to adjacent surface Pt atoms, and the two black circles of C2H4 bonded to adjacent surface Pt atoms. Stage 3 shows a C2H5 group bonded to one surface Pt atom and one open circle bonded to an adjacent Pt atom. Stage 4 shows one intact C2H6 molecule above the bare Pt surface. No other particles, labels, text, or annotations appear.
Particulate representation of the four stages of the \(\text{Pt}\)-catalyzed hydrogenation of \(\text{C}_2\text{H}_4\).
The hydrogenation of ethene to form ethane in the presence of a solid platinum catalyst is represented by the following chemical equation:

\[ \text{C}_2 ext{H}_4\text{(g)} + \text{H}_2\text{(g)} \xrightarrow{\text{Pt(s)}} \text{C}_2\text{H}_6\text{(g)} \]

A proposed particulate-level mechanism for this heterogeneous catalytic process is shown in the four sequential stages below.

Based on the representations, which of the following best explains how the interaction between the reactant molecules and the \(\text{Pt}\) catalyst surface lowers the activation energy (\(E_a\)) of the reaction compared to the uncatalyzed gas-phase reaction?

Log In to Continue

Accounts are free! Log in to try this question, see explanations, save progress, and more!

Similar Questions

Tools for a 5

The Quiz Lab library of AP Physics quizzes AP aligned mock tests to help you get a 5. With grading, adaptive explanations, and more. Find a Quiz Find, solve, and grade every AP FRQ ever. Find an FRQ Stuck on AP Chemistry? Get unstuck with an AP specialist.1 to 1 tutors who know the exam inside out. Understand weeks of material in a single session.Find a Tutor Learn AP Physics from scratch, quickly. This is the only course you'll need for the year. A self-paced course with everything you need to get a 5. Trusted by over 15,000 students and 200+ schools. Learn fast, or we'll refund your purchase, backed by our 100% satisfaction guarantee. Explore the Course