Student Exploration: Feel the Heat

Vocabulary: calorimeter, conductor, controlled experiment, dissolve, endothermic, exothermic,

insulator, solute, solution, solvent, surroundings, system

Prior Knowledge Questions (Do these BEFORE using the Gizmo.)

Eduardo hurts his knee during a basketball game. The trainer applies a cold pack, which gets

cold after being squeezed. The next day, Eduardo’s friend Beth is going sledding. Beth buys

some hand warmers and puts them into her gloves. All morning, her hands stay toasty warm.

1. How do you think these devices work?

2. Where do you think the “cold” and the heat comes from?

Gizmo Warm-up

As you saw with the instant cold pack and the hand warmers, some

reactions absorb energy while others release it. In the Feel the Heat

Gizmo, you will explore these energy changes while making your own

hot and cold packs.

To begin, select the TEST POWDERS tab. Drag a bottle of NaC2H3O2

(sodium acetate) from the shelf. Using the sliders, decide how much

water and powder to add. Note the beginning temperature, and then

press Play ( ) to see what happens.

1. Did the temperature go up or down?

2. Experiment with different powders until you find one that produces the opposite effect.

What powder did you use?

 There are more than likely 2

solutions inside the packets. When squeezed, it breaks the

inside containers combining the solutions and creating either

an endothermic reaction for a cold pack or an exothermic

reaction for a heat pack.

 For the endothermic,

when the substances mix, the reaction absorbs all the heat

inside the container, dropping the temperature of the packet.

For the exothermic, when the substances mix, the reaction

gives off heat, raising the temperature of the packet.

It went up

NH4NO3