Design an experiment to test substances [tex][tex]$X, Y$[/tex][/tex], and [tex][tex]$Z$[/tex][/tex] to determine which one is a catalyst for the reaction [tex][tex]$A + B \rightarrow C$[/tex][/tex].

- When [tex][tex]$C$[/tex][/tex] is created, bubbles form.
- When [tex][tex]$10 \, \text{mL}$[/tex][/tex] of [tex][tex]$A$[/tex][/tex] is added to [tex][tex]$10 \, \text{mL}$[/tex][/tex] of [tex][tex]$B$[/tex][/tex], the reaction takes twenty seconds.

Use this information to design your experiment.

[tex][tex]$\square$[/tex][/tex]



Answer :

To determine which of the substances ([tex]$X, Y, Z$[/tex]) acts as a catalyst for the reaction [tex]\( A + B \rightarrow C \)[/tex], follow these experimental steps:

### 1. Setting Up Control Experiment
First, establish a baseline for the reaction without any catalyst.
1. Measure 10 mL of substance [tex]\( A \)[/tex] and 10 mL of substance [tex]\( B \)[/tex].
2. Mix them together in a reaction vessel.
3. Record the time taken for the reaction to complete. Note that the initial reaction takes twenty seconds.

### 2. Testing with Substances X, Y, and Z
You will now test each substance ([tex]\( X, Y, \)[/tex] and [tex]\( Z \)[/tex]) individually to see if they act as catalysts. A catalyst will speed up the reaction without being consumed in the process.

#### Experiment with Substance X
1. Measure 10 mL of substance [tex]\( A \)[/tex] and 10 mL of substance [tex]\( B \)[/tex].
2. Add a small amount of substance [tex]\( X \)[/tex] to the mixture (keep the amount consistent for each substance to ensure fair comparison).
3. Mix them together and start timing the reaction.
4. Record the time taken for the reaction to complete (time taken for bubbles to stop forming).

#### Experiment with Substance Y
5. Measure 10 mL of substance [tex]\( A \)[/tex] and 10 mL of substance [tex]\( B \)[/tex].
6. Add the same amount of substance [tex]\( Y \)[/tex] as the one used for substance [tex]\( X \)[/tex].
7. Mix them together and start timing the reaction.
8. Record the time taken for the reaction to complete.

#### Experiment with Substance Z
9. Measure 10 mL of substance [tex]\( A \)[/tex] and 10 mL of substance [tex]\( B \)[/tex].
10. Add the same amount of substance [tex]\( Z \)[/tex] (consistently with previous tests).
11. Mix them together and start timing the reaction.
12. Record the time taken for the reaction to complete.

### 3. Comparing Results
Compare the times recorded for each of the tests:
- The substance that significantly reduces the time required for the reaction compared to the control experiment is the catalyst because it increases the rate of reaction.
- If one of the substances, say [tex]\( X \)[/tex], reduces the reaction time significantly (much less than the original twenty seconds), then [tex]\( X \)[/tex] is the catalyst.
- Ensure to use a fresh mixture of [tex]\( A \)[/tex] and [tex]\( B \)[/tex] for each new substance to avoid cross-contamination and inconsistent results.

### 4. Replication and Verification
To confirm your results:
- Repeat the experiments multiple times to ensure consistency and accuracy.
- Ensure all other conditions (temperature, pressure, volumes) remain constant across all experiments.

By comparing the reaction times with and without the substances [tex]\( X, Y, \)[/tex] and [tex]\( Z \)[/tex], you can determine the catalytic effect and identify which substance acts as the catalyst for the reaction [tex]\( A + B \rightarrow C \)[/tex].

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