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Coffee Cup Calorimeter

Some chemical reactions release thermal energy and some reactions gain thermal energy. Sam and Alex want to make a calorimeter, which is a device that can measure thermal energy (heat) changes during chemical reactions involving a sample. Sam and Alex design their device to measure these changes. A drawing of their calorimeter is shown below.

The illustration titled 'Coffee Cup Calorimeter' shows nested Styrofoam cups as insulation and a cork stopper that seals the top cup. Inside the cup is a sample cube and water that surrounds the sample. A stirrer and thermometer are inserted through the cork stopper into the cup. The bottoms of the stirrer and thermometer are in the water.

As a reaction occurs involving the sample, changes occur in the system based on whether the reaction gains or releases thermal energy.

Multiple Select Question
The students are given an unknown sample to place in the calorimeter, as shown in the passage. They measure the initial and final temperatures of the water in the calorimeter. The temperatures are shown below.

Initial temperature is 24 degrees celsius. Final temperature is 26 degrees celsius.

Select THREE statements below that describe energy or matter for this reaction in the coffee cup calorimeter system.

A.
Before the reaction begins, the water and the sample are present in the same state of matter.

B.
The temperature measurement describes the average potential energy of the particles of matter in the cup system.

C.
The reaction caused energy to be released into the surrounding water.

D.
The reaction absorbed energy from the surrounding water.

1 answer

To determine the correct statements regarding the reaction in the coffee cup calorimeter based on the temperature change observed, we analyze the information given:

  1. The initial temperature of the water is 24 degrees Celsius.
  2. The final temperature of the water is 26 degrees Celsius.
  3. Since the temperature of the water increased, this indicates that energy was absorbed from the reaction.

Now let's evaluate the given statements:

A. Before the reaction begins, the water and the sample are present in the same state of matter.

  • This statement is likely incorrect because it is not guaranteed that the sample and water are in the same state of matter. The sample could be a solid (like a cube) while the water is a liquid.

B. The temperature measurement describes the average potential energy of the particles of matter in the cup system.

  • This statement is misleading. Temperature is more directly related to the average kinetic energy of the particles, not potential energy. This statement is not entirely correct.

C. The reaction caused energy to be released into the surrounding water.

  • This statement is incorrect, as the water's temperature increased; if energy were released, the temperature would have decreased.

D. The reaction absorbed energy from the surrounding water.

  • This statement is correct. Since the temperature of the water increased, it indicates that the reaction absorbed energy (making the water lose some thermal energy).

Therefore, the correct statements regarding the reaction in the coffee cup calorimeter system are:

  • D. The reaction absorbed energy from the surrounding water.

Since only one statement is correct based on the provided temperature change analysis, and only one option (D) stands out as accurate, it seems there may have been a misunderstanding in your instruction to select three statements.

If there were additional context (for example, if other options were available), it might change the outcome, but based solely on the provided data, only D is correct.