Fountain Connection

Introduction

Produce an exciting bubbling fountain and demonstrate the power of air pressure.

Concepts

  • Fountains
  • Vacuum
  • Gravity
  • Air pressure

Materials

Food coloring*
Water, ≈1.5 L
Fountain connection includes a connector and 2 clear, plastic bottles
Hair dryer
Scissors*
Soda bottles, 2-L,3
Tray*
*Optional

Safety Precautions

This activity is considered to be nonhazardous. Follow all normal laboratory guidelines.

Disposal

The assembled fountain may be reused many times.

Procedure

  1. The clear plastic tubes have holes drilled near one end. Insert this end into the connector approximately one-fourth inch.
  2. Clean out two plastic 2-liter soda bottles and remove the labels using hot air from a hair dryer. The plastic tubes can be shortened to fit smaller bottles. Do not cut the ends of the tubes with the small holes.
  3. Fill one bottle ¾ full with clear or colored water and connect the two bottles together. The fountain will erupt every time you turn the bottle over (see Figure 1).
{12999_Procedure_Figure_1_Basic fountain}
  1. To demonstrate that a partial vacuum is formed in the upper bottle, start the fountain and unscrew the lower bottle. Lift the fountain up as shown in Figure 2. Air rushes up the fountain tube to occupy the empty space and takes water with it. Place a tray underneath to catch any spilled water.
{12999_Procedure_Figure_2_Partial pressure}

Correlation to Next Generation Science Standards (NGSS)†

Science & Engineering Practices

Developing and using models

Disciplinary Core Ideas

MS-PS2.A: Forces and Motion
MS-PS3.B: Conservation of Energy and Energy Transfer
MS-PS3.C: Relationship between Energy and Forces
HS-PS2.A: Forces and Motion
HS-PS3.B: Conservation of Energy and Energy Transfer
HS-PS3.C: Relationship between Energy and Forces

Crosscutting Concepts

Cause and effect
Systems and system models
Energy and matter

Performance Expectations

HS-PS3-2. Develop and use models to illustrate that energy at the macroscopic scale can be accounted for as a combination of energy associated with the motion of particles (objects) and energy associated with the relative position of particles (objects).

Discussion

Hero of Alexandria (ca 62 A.D.) described a water fountain that used compressed air to lift water to a point higher than its origin. The result was a fountain that seemed to defy both logic and the laws of nature. A closer study of your fountain will reveal the principles of its operation.

When the bottles are inverted, gravity pulls the water from the upper bottle down through the lower tube and compresses the air in the lower bottle. When water leaves the upper bottle, a decrease in pressure, or partial vacuum, is formed. Air is then forced from the lower bottle, up the fountain tube, and takes the place of the water that is leaving the upper bottle.

If the clear tubes are examined near where they enter the bottle connector, several small holes will be visible. When the bottle is turned over, water runs into these small holes and is pushed upwards by the air with enough force to form the fountain at the top of the bottle. This is the same type of action that moves water in fish tank filters and some types of coffee percolators. The tube in the lower bottle has no effect on the formation of the fountain. Try the fountain connector with one tube removed.

†Next Generation Science Standards and NGSS are registered trademarks of Achieve. Neither Achieve nor the lead states and partners that developed the Next Generation Science Standards were involved in the production of this product, and do not endorse it.