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The typical speed of a reaction releases gas every twenty seconds for two minutes. The chart lists four substances that were added to the reaction at different times.




Substance		Time addedGas release time

W		21 sec45 sec

X		46 sec56 sec

Y		57 sec70 sec

Z		71 sec92 sec






Which statement best summarizes the chart?

ASubstances W and Y are catalysts, and substances X and Z are inhibitors.
BSubstance $W$ is an inhibitor, and substances $X, Y$, and $Z$ are catalysts.
CSubstances W and Z are inhibitors, and substances X and Y are catalysts.

Verified Answer :

  • Establish the baseline gas release schedule at 20, 40, 60, 80, 100, and 120 seconds.
  • Compare each substance's actual release time to the next scheduled interval in the baseline.
  • Classify substances as catalysts if the actual time is earlier than the baseline and as inhibitors if it is later.
  • Identify that substances W and Z (45s > 40s and 92s > 80s) act as inhibitors, while substances X and Y (56s < 60s and 70s < 80s) act as catalysts.
  • Final answer: \(\boxed{\text{Substances W and Z are inhibitors, and substances X and Y are catalysts.}}\)

Explanation

  1. Understanding the Reaction Baseline

To determine whether each substance is a catalyst or an inhibitor, we first identify the standard gas release schedule. The reaction releases gas every 20 seconds, meaning the baseline schedule is: 20, 40, 60, 80, 100, and 120 seconds. A substance is a catalyst if it causes the gas to be released earlier than the next scheduled time, and an inhibitor if it causes the gas to be released later than the next scheduled time.

  1. Evaluating Substances W, X, Y, and Z

Now we analyze each substance by comparing the gas release time to the next scheduled interval:

  • Substance W: Added at 21 seconds. The next scheduled release time is 40 seconds. The actual release is at 45 seconds. Since 45 seconds > 40 seconds, substance W is an inhibitor.
  • Substance X: Added at 46 seconds. The next scheduled release time is 60 seconds. The actual release is at 56 seconds. Since 56 seconds < 60 seconds, substance X is a catalyst.
  • Substance Y: Added at 57 seconds. The next scheduled release time is 80 seconds. The actual release is at 70 seconds. Since 70 seconds < 80 seconds, substance Y is a catalyst.
  • Substance Z: Added at 71 seconds. The next scheduled release time is 80 seconds. The actual release is at 92 seconds. Since 92 seconds > 80 seconds, substance Z is an inhibitor.
  1. Conclusion

Comparing our findings to the given options:

  • W (Inhibitor)
  • X (Catalyst)
  • Y (Catalyst)
  • Z (Inhibitor)

The summary that matches these results is: "Substances W and Z are inhibitors, and substances X and Y are catalysts." Therefore, the third statement is the correct one.

Examples

In a chemical plant, reactions must be tightly controlled. Engineers use catalysts to speed up reactions, increasing productivity without raising temperatures, which saves energy. Conversely, inhibitors are used to slow down runaway reactions, ensuring safety and precision. By analyzing the timing of reaction events, engineers can categorize substances effectively and optimize the manufacturing process.

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