AP Chemistry
6.7 Bond Enthalpies
6.1 Endothermic and Exothermic Processes
A student investigates the thermochemistry of the stepwise hydrogenation of ethyne, represented by the two balanced chemical equations below.
\[ \text{Reaction 1: } \text{C}_2\text{H}_2\text{(g)} + \text{H}_2\text{(g)} \rightarrow \text{C}_2\text{H}_4\text{(g)} \]
\[ \text{Reaction 2: } \text{C}_2\text{H}_4\text{(g)} + \text{H}_2\text{(g)} \rightarrow \text{C}_2\text{H}_6\text{(g)} \]
The student references the following table of average bond enthalpies:
Based on the data in the table, which of the following correctly compares the standard enthalpy change of Reaction 1 (\(\Delta H_1^\circ\)) to that of Reaction 2 (\(\Delta H_2^\circ\)) and provides the correct justification?
\[ \text{Reaction 1: } \text{C}_2\text{H}_2\text{(g)} + \text{H}_2\text{(g)} \rightarrow \text{C}_2\text{H}_4\text{(g)} \]
\[ \text{Reaction 2: } \text{C}_2\text{H}_4\text{(g)} + \text{H}_2\text{(g)} \rightarrow \text{C}_2\text{H}_6\text{(g)} \]
The student references the following table of average bond enthalpies:
| Bond | Average bond enthalpy (\(\text{kJ/mol}\)) |
|---|---|
| \(\text{C}-\text{C}\) | \(350\) |
| \(\text{C}=\text{C}\) | \(610\) |
| \(\text{C}\equiv\text{C}\) | \(840\) |
| \(\text{C}-\text{H}\) | \(410\) |
| \(\text{H}-\text{H}\) | \(435\) |
Based on the data in the table, which of the following correctly compares the standard enthalpy change of Reaction 1 (\(\Delta H_1^\circ\)) to that of Reaction 2 (\(\Delta H_2^\circ\)) and provides the correct justification?
Similar Questions
Tools for a 5
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.Book a SessionSee all our elite tutors
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