Imagine you are in a laboratory. You are exploring the following reaction: A + B → C

Question

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

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

Answer 1

To determine which of the unknown substances (X, Y, or Z) is a catalyst for the reaction \( A + B \rightarrow C \), we can design a simple experiment based on comparing the effect of each substance on the reaction time. A catalyst will speed up the reaction without being consumed in the process. Here is a step-by-step outline of the experiment:

Materials Needed

1. Unknown substances X, Y, and Z
2. Solutions of A and B (10 mL of each)
3. Stopwatch or timer
4. Graduated cylinder or pipettes for accurate measurement
5. Beakers or reaction vessels (at least 4)
6. Thermometer (to ensure consistent temperature)
7. Stirring device (magnetic stirrer or stirring rod)
8. Safety equipment (gloves, goggles, lab coat)

Experimental Procedure

1. Control Reaction:

   • Prepare a control reaction without any additives.
   • Combine 10 mL of A with 10 mL of B in a beaker and start the stopwatch as soon as the solutions are mixed. Record the time taken for the reaction to complete (the time until bubbles stop forming). This should be around 20 seconds as previously observed.

2. Testing Substance X:

   • In a new beaker, add 10 mL of A and 10 mL of B.
   • Add a measured amount of substance X (for example, 0.5 grams) to the mixture.
   • Start the stopwatch immediately after mixing. Record the time it takes for the reaction to complete.

3. Testing Substance Y:

   • Repeat the above step using substance Y instead of X.
   • Again, note the reaction time.

4. Testing Substance Z:

   • Repeat the experiment with substance Z.
   • Record the time taken to complete the reaction.

5. Control Variables:

   • Ensure that the experiments are conducted at a constant temperature to prevent temperature differences from affecting the reaction rate.
   • Use the same quantities for A and B each time to keep the reaction conditions consistent.

6. Repeats:

   • Consider repeating each test at least two more times to ensure reproducibility of the results, averaging the times obtained for better accuracy.

Data Analysis

• Compare the reaction times: Analyze the recorded times from each trial.
  • If the addition of substance X significantly decreases the time taken for the reaction compared to the control (around 20 seconds), it suggests that substance X is a catalyst.
  • If substance Y or Z shows a similar reduction in time, it may be a catalyst instead.
  • If there is no significant change in reaction times with all substances tested, it indicates that none of them is a catalyst.

Conclusion

Based on the results, determine which substance, if any, acts as a catalyst for the reaction \( A + B \rightarrow C \) by observing which substance notably decreases the reaction time compared to the control reaction. Document the findings and discuss any potential implications or further questions arising from the experiment.