Question

Cold Pack Investigation
People use self-warming and self-cooling devices for many purposes such as keeping drinks cold or food warm. Medical professionals also use these types of devices to store medicines and other substances that need to stay colder than room temperature. These cooling and warming devices use a chemical reaction to produce their chilling and warming effects. Compounds combine in endothermic (heat absorbing) or exothermic (heat releasing) reactions within these devices to help them keep items cool or warm.

Jacob and Natalie are asked by their science teacher to design a warming or cooling device. They decide to design a cold pack that can be used to help keep food cool. Jacob and Natalie read about different substances that can be used inside cold packs and learn that most cold packs use endothermic reactions to cool objects. They find the table below while researching.

The table titled 'Effect on Temperature of Different Substances' shows Sample, Composition, Initial temperature in degrees Celsius and Final temperature in degrees Celsius. Sample 1's composition is Ammonium nitrate, urea and water, Initial temperature is 22.0, and final temperature is negative 17.5. Sample 2's composition is Ammonium nitrate and water, Initial temperature is 22.0, and final temperature is negative 4.0. Sample 3's composition is Urea and water, Initial temperature is 22.0, and final temperature is 4.0. Sample 4's composition is Water, initial temperature is 22.0, and final temperature is 22.0

Multiple Choice Question
Which evidence provided BEST supports the statement that cold packs use endothermic reactions to cool objects?

A.
The initial temperature in Test 4 was the same and the final temperature.

B.
The initial temperatures for Tests 1, 2, and 3 were lower than the final temperatures in the tests.

C.
The initial temperatures for Tests 1, 2, and 3 were higher than the final temperatures in the tests.

D.
The initial temperature and the final temperature for Test 3 were both positive numbers.

Answer 1

The best evidence that supports the statement that cold packs use endothermic reactions to cool objects is:

**C. The initial temperatures for Tests 1, 2, and 3 were higher than the final temperatures in the tests.**

This option indicates that the substances in Tests 1, 2, and 3 absorbed heat (hence the decrease in temperature), which is characteristic of an endothermic reaction.