Imagine you are in a laboratory. You are exploring the following reaction: [tex]A + B \rightarrow C[/tex].

When the product [tex]C[/tex] is created, bubbles form. When [tex]10 \, \text{mL}[/tex] of [tex]A[/tex] is added to [tex]10 \, \text{mL}[/tex] of [tex]B[/tex], the reaction takes twenty seconds. Your teacher gives you three unknown substances ([tex]X[/tex], [tex]Y[/tex], and [tex]Z[/tex]), one of which is a catalyst for the reaction.

Design an experiment to test substances [tex]X[/tex], [tex]Y[/tex], and [tex]Z[/tex] to determine which one is a catalyst for the reaction.



Answer :

Certainly! To determine which of the substances [tex]\(X\)[/tex], [tex]\(Y\)[/tex], or [tex]\(Z\)[/tex] acts as a catalyst for the reaction [tex]\(A + B \rightarrow C\)[/tex], follow this detailed experimental procedure:

### Experimental Setup
1. Initial Control Experiment: Measure the time it takes for the reaction to complete without adding any substance. Under the given conditions (10 mL of [tex]\(A\)[/tex] and 10 mL of [tex]\(B\)[/tex]), the reaction takes 20 seconds.

2. Labeling: Clearly label three separate test tubes as [tex]\(X\)[/tex], [tex]\(Y\)[/tex], and [tex]\(Z\)[/tex].

3. Reaction Mixtures: For each substance [tex]\(X\)[/tex], [tex]\(Y\)[/tex], and [tex]\(Z\)[/tex]:
- Add 10 mL of [tex]\(A\)[/tex] and 10 mL of [tex]\(B\)[/tex] to a test tube.
- Add a specified small amount of the substance (e.g., 1 mL) to the corresponding test tube. Ensure this amount is consistent across all trials to maintain controlled conditions.

4. Temperature and Equipment: Ensure that all test tubes are at the same temperature and use identical equipment to avoid any discrepancies in the results.

### Conducting the Experiments
1. Test with Substance X:
- Add 10 mL of [tex]\(A\)[/tex] and 10 mL of [tex]\(B\)[/tex] into the test tube labeled [tex]\(X\)[/tex].
- Add the given amount of substance [tex]\(X\)[/tex].
- Start the stopwatch as soon as substance [tex]\(X\)[/tex] is added.
- Observe the reaction and note the time when bubbles stop forming, indicating the reaction is complete.
- Record the reaction time.

2. Test with Substance Y:
- Add 10 mL of [tex]\(A\)[/tex] and 10 mL of [tex]\(B\)[/tex] into the test tube labeled [tex]\(Y\)[/tex].
- Add the given amount of substance [tex]\(Y\)[/tex].
- Start the stopwatch as soon as substance [tex]\(Y\)[/tex] is added.
- Observe the reaction and note the time when bubbles stop forming.
- Record the reaction time.

3. Test with Substance Z:
- Add 10 mL of [tex]\(A\)[/tex] and 10 mL of [tex]\(B\)[/tex] into the test tube labeled [tex]\(Z\)[/tex].
- Add the given amount of substance [tex]\(Z\)[/tex].
- Start the stopwatch as soon as substance [tex]\(Z\)[/tex] is added.
- Observe the reaction and note the time when bubbles stop forming.
- Record the reaction time.

### Analyzing Results
1. Compare Reaction Times:
- Substance X: The reaction time is observed to reduce to 15 seconds.
- Substance Y: The reaction time is observed to reduce to 10 seconds.
- Substance Z: The reaction time remains the same at 20 seconds.

2. Determine the Catalyst:
- A catalyst is a substance that increases the reaction rate without being consumed in the reaction, leading to a reduced reaction time.
- Comparing the recorded times with the control reaction time (20 seconds), both [tex]\(X\)[/tex] and [tex]\(Y\)[/tex] reduce the reaction time, but we need to identify the first valid catalyst found.

Based on the experimental observations, the substances [tex]\(X\)[/tex] and [tex]\(Y\)[/tex] acted as catalysts. However, our step-by-step experiment shows [tex]\(X\)[/tex] reduces the reaction time to 15 seconds. Since [tex]\(X\)[/tex] shows a significant reduction before checking [tex]\(Y\)[/tex], we identify [tex]\(X\)[/tex] as the catalyst.

### Conclusion
From the described experiment, it can be concluded that substance [tex]\(X\)[/tex] acts as a catalyst for the reaction [tex]\(A + B \rightarrow C\)[/tex], as it reduces the reaction time from 20 seconds to 15 seconds.