In this experiment, you’ll perform three trials. Follow these steps to proceed with the first trial: Fill one of the two bowls with very warm water, between 45°C and 49°C (113°F and 120°F). Use the thermometer to measure the temperature of the water in degrees Celsius, and record it in the provided table.
Stay safe! To avoid burns, do not use water hotter than 49°C.
Fill the other bowl with ice water. The temperature of the water in this bowl should be between 5°C and 10°C (41°F and 50°F). Use the thermometer to measure the temperature of the water in degrees Celsius, and record it in the table.
With the bottle uncapped, hold the bottle in the bowl of warm water. The bottle should be mostly under water, but the mouth of the bottle should be above the water so that water doesn’t enter the bottle. Hold the bottle in this position for three minutes, using the stopwatch to track the time. The air inside the bottle will come to the same temperature as the water in the bowl. Cap the bottle tightly, and then remove it from the warm water.

a bottle placed inside a vessel of warm water with the mouth of the bottle just above the level of the water in the vessel; after 3 minutes, the bottle is removed from the water and capped
Hold the bottle by the neck to avoid prolonged skin contact with the warm water.

Quickly transfer the bottle to the bowl of cold water as shown in the image. Turn the bottle upside down, and immerse it in the bowl (left). Now remove the cap (right). Notice that some water will enter the bottle. Hold the bottle in the upside-down position in the cold water for three minutes. Time yourself using a stopwatch, like before. The air inside the bottle will now come to the same temperature as the water. Take care that the bottle remains vertical in the upside-down position. If it tips far enough that air bubbles start to escape, you’ll need to restart the procedure.

two images of an inverted bottle immersed in a vessel containing water: the bottle is shown capped bottle (left) and without a cap, partially filled with water, with empty air space above the water level in the bottle (right)
Try to minimize prolonged skin contact with the cold water.

After three minutes, move the bottle up in the water until the level of the water inside the bottle is precisely even with the level of the water outside the bottle. This position ensures that the pressure of the air in the bottle equals the pressure of the atmospheric air. Be sure to keep the mouth of the bottle in the water (image on left). After the water levels are aligned, cap the bottle tightly while holding the bottle still (image on right), and then remove it from the water.

two images of an inverted bottle in a vessel containing water with the water inside the bottle even with the water line; the bottle shown uncapped (left) and then capped (right)
Set the bottle upright on a flat surface, and then remove the cap. Pour the water from the bottle into a graduated cylinder or other measuring tool to measure its volume. Record this measurement in the table below for trial 1.
Repeat steps 1–6 two more times to complete trials 2 and 3. Try to keep the temperature of the hot water constant across the trials as much as possible. Record your data in the table.