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Approaching the Same Mixture From Two Sides 4 questions
Approaching the Same Mixture From Two Sides
Base your answers on the information provided and your knowledge of chemistry. Use the 2025 Chemistry Reference Tables as needed.
A reaction model lets a particle change between forms R and S. Each run contains 100 particles and stays at the same temperature. The class records the number of S particles as the mixture changes.
| Run | S at 0 s | S at 20 s | S at 40 s | S at 80 s | S at 120 s |
|---|---|---|---|---|---|
| P | 0 | 35 | 55 | 60 | 60 |
| Q | 100 | 78 | 66 | 60 | 60 |
Question 1
Which comparison supports the same equilibrium composition from both starting points?
- P and Q have the same initial count.
- P and Q have the same count at 20 s.
- P and Q have the same stable count at the final two observations.
- The count of S increases in both runs.
Question 2
Use the first 20 seconds to show that the net change can go in either direction in this model.
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A third run starts with 100 S, as Q did, and uses a catalyst. It shows 60 S at both 20 s and 40 s. The temperature and total number of particles are unchanged.
Question 3
Compare the new run with Q. What does the evidence show about how quickly the mixture approaches its stable composition?
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Question 4
Describe how the count of S could stay at 60 while particles continue changing form. Include both directions of change.
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