Answered

Three treatments of different starting materials are listed.




Substance		Characteristics

1		The substance was heated and then placed in an ice bath.

2		The substance was in a salt solution of 2M and later placed in a solution of 4M to cause a reaction.

3		The substance was hammered and broken into pieces.






Which statement explains the treatments?


ASubstance 1 was activated by a decrease in temperature, Substance 2 was activated by the change in concentration, and Substance 3 decreased the surface area.
BSubstance 1 was activated by a decrease in temperature, Substance 2 was activated by the change in pressure, and Substance 3 increased the surface area.
CSubstance 1 was activated by the heat and inactivated by ice, Substance 2 was activated by the change in pressure, and Substance 3 decreased the surface area.
DSubstance 1 was activated by the heat and inactivated by ice, Substance 2 was activated by the change in concentration, and Substance 3 increased the surface area.

Verified Answer :

  • Substance 1 is activated by heat and inactivated by cold (ice).
  • Substance 2 experiences a change in concentration when moved from a 2 M to 4 M salt solution.
  • Substance 3 increases its surface area by being broken into smaller pieces.
  • The correct choice is: \(\boxed{\text{Substance 1 was activated by the heat and inactivated by ice, Substance 2 was activated by the change in concentration, and Substance 3 increased the surface area.}}\)

Explanation

  1. Analyzing the Treatments

We analyze the effects of three specific treatments on different substances to determine the correct scientific explanation for each.

  • Substance 1: The substance is heated and then placed in an ice bath. Heating is a common method to provide activation energy, initiating or accelerating a process. Conversely, an ice bath is used to rapidly cool the substance, which typically stops or slows down (inactivates) the process.
  • Substance 2: The substance is transferred from a 2 M salt solution to a 4 M salt solution to induce a reaction. A change in the molarity (2 M to 4 M) is a change in concentration. In chemical kinetics, increasing the concentration of reactants often increases the rate of reaction by providing more particles per unit volume.
  • Substance 3: The substance is hammered and broken into pieces. Mechanical force reduces a large solid piece into smaller fragments. This increases the total surface area exposed to the surrounding environment or reactants, which generally leads to a faster reaction rate for solid-phase processes.
  1. Evaluating the Statements

Now we evaluate the given options based on our analysis:

  1. "Substance 1 was activated by a decrease in temperature, Substance 2 was activated by the change in concentration, and Substance 3 decreased the surface area." - Incorrect, because breaking a solid increases, not decreases, surface area.
  2. "Substance 1 was activated by a decrease in temperature, Substance 2 was activated by the change in pressure, and Substance 3 increased the surface area." - Incorrect, because Substance 1's activation is driven by heat, and Substance 2's change is in concentration, not pressure.
  3. "Substance 1 was activated by the heat and inactivated by ice, Substance 2 was activated by the change in pressure, and Substance 3 decreased the surface area." - Incorrect, because Substance 2's change is in concentration, and Substance 3 increases the surface area.
  4. "Substance 1 was activated by the heat and inactivated by ice, Substance 2 was activated by the change in concentration, and Substance 3 increased the surface area." - This statement correctly aligns with the physical and chemical principles of all three processes.
  1. Conclusion

Based on the systematic evaluation, the fourth statement provides the accurate explanation for all three treatments. The final answer is that Substance 1 was activated by heat and inactivated by ice, Substance 2 was activated by the change in concentration, and Substance 3 increased the surface area. \(\boxed{\text{Substance 1 was activated by the heat and inactivated by ice, Substance 2 was activated by the change in concentration, and Substance 3 increased the surface area.}}\)

Examples

In a laboratory, scientists often use these techniques to control chemical reactions. For example, when performing an organic synthesis, a researcher might heat a mixture to start a reaction, then use an ice bath to "quench" it, effectively stopping any further reaction at a precise time. Similarly, knowing that higher concentrations and larger surface areas speed up reactions allows chemists to optimize industrial processes, such as the Haber process for ammonia production or the dissolution of solid catalysts, to be as efficient as possible.

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