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

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

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



Answer :

To determine which among the substances [tex]\( X \)[/tex], [tex]\( Y \)[/tex], and [tex]\( Z \)[/tex] is a catalyst for the reaction [tex]\( A + B \rightarrow C \)[/tex], we can design the following step-by-step experiment:

### Step-by-Step Experimental Design

#### Preparation

1. Prepare Reagents:
- Ensure you have clean containers and precise measuring equipment.
- Label containers clearly for each substance: [tex]\( A \)[/tex], [tex]\( B \)[/tex], [tex]\( X \)[/tex], [tex]\( Y \)[/tex], and [tex]\( Z \)[/tex].

#### Control Experiment (Without Catalyst)

2. Set Up the Control Reaction:
- Measure and add [tex]\( 10 \, \text{mL} \)[/tex] of substance [tex]\( A \)[/tex] and [tex]\( 10 \, \text{mL} \)[/tex] of substance [tex]\( B \)[/tex] into a clean reaction container.

3. Measure Reaction Time:
- Start a stopwatch as soon as both substances are mixed.
- Observe the formation of bubbles and record the exact time it takes for the reaction to complete. This time is your control time, which we already know to be [tex]\( 20 \)[/tex] seconds.

4. Record the Control Time:
- Note: [tex]\( \text{Control Time} = 20 \)[/tex] seconds

#### Testing with Substances [tex]\( X \)[/tex], [tex]\( Y \)[/tex], and [tex]\( Z \)[/tex]

5. Test with Substance [tex]\( X \)[/tex]:
- Measure and add [tex]\( 10 \, \text{mL} \)[/tex] of substance [tex]\( A \)[/tex] and [tex]\( 10 \, \text{mL} \)[/tex] of substance [tex]\( B \)[/tex] into a clean reaction container.
- Add a small measured amount of substance [tex]\( X \)[/tex] to the mixture of [tex]\( A \)[/tex] and [tex]\( B \)[/tex].
- Start the stopwatch as soon as the substances are mixed.
- Observe the formation of bubbles and record the exact reaction time in seconds.

6. Repeat for Substances [tex]\( Y \)[/tex] and [tex]\( Z \)[/tex]:
- Perform the exact same steps as for substance [tex]\( X \)[/tex], but this time add either substance [tex]\( Y \)[/tex] or [tex]\( Z \)[/tex] respectively.
- Ensure precise measurements and start the stopwatch immediately as mixing occurs.
- Record the reaction time for each test with substance [tex]\( Y \)[/tex] and [tex]\( Z \)[/tex].

#### Data Recording and Analysis

7. Record Reaction Times:
- Let’s denote the recorded reaction times as follows:
- [tex]\( t_X = \)[/tex] time in seconds with substance [tex]\( X \)[/tex]
- [tex]\( t_Y = \)[/tex] time in seconds with substance [tex]\( Y \)[/tex]
- [tex]\( t_Z = \)[/tex] time in seconds with substance [tex]\( Z \)[/tex]

8. Analyze the Results:
- Compare the reaction times [tex]\( t_X \)[/tex], [tex]\( t_Y \)[/tex], and [tex]\( t_Z \)[/tex] with the control time of [tex]\( 20 \)[/tex] seconds.
- The substance that significantly reduces the reaction time (compared to the control time of [tex]\( 20 \)[/tex] seconds) is identified as the catalyst.

### Expected Outcome Interpretation

- If the reaction time with substance [tex]\( X \)[/tex] is significantly less than [tex]\( 20 \)[/tex] seconds, then substance [tex]\( X \)[/tex] is likely the catalyst.
- Similarly, if the reaction time with substance [tex]\( Y \)[/tex] or [tex]\( Z \)[/tex] is significantly less than [tex]\( 20 \)[/tex] seconds, then that substance is the catalyst.

### Summary of Key Data Points:

- Control Reaction Time: [tex]\( 20 \)[/tex] seconds
- Variable Reaction Times with Substances:
- Substance [tex]\( X \)[/tex]: Record in seconds
- Substance [tex]\( Y \)[/tex]: Record in seconds
- Substance [tex]\( Z \)[/tex]: Record in seconds

By following this detailed experimental procedure, you will be able to identify which substance among [tex]\( X \)[/tex], [tex]\( Y \)[/tex], and [tex]\( Z \)[/tex] acts as a catalyst for the reaction [tex]\( A + B \rightarrow C \)[/tex].