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Counting Both Directions at Equilibrium 4 questions
Counting Both Directions at Equilibrium
Base your answers on the information provided and your knowledge of chemistry. Use the 2025 Chemistry Reference Tables as needed.
An exhibit models a reversible change from A to B. Each forward event changes one A into one B, and each reverse event changes one B into one A. The counters report both kinds of event over a 10-second window. The system is closed and temperature stays fixed.
| Window | Forward events | Reverse events |
|---|---|---|
| Before the composition settles | 12 | 8 |
| After the composition settles | 9 | 9 |
| After adding a catalyst to the settled mixture | 18 | 18 |
Question 1
In which window does the number of B particles increase on balance?
- Only before the composition settles
- Only after the composition settles
- Only after adding the catalyst
- In all three windows
Question 2
Complete the table with the average forward and reverse rates. Use the observation window.
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Question 3
A student says the catalyst shifted the mixture toward B because the forward counter doubled. Evaluate the claim using both counters.
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A replacement counter reports 36 forward events and 36 reverse events from the same catalyzed mixture. Its observation window is 20 seconds.
Question 4
Explain whether the replacement counter supports a further rate increase.
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