Boiling in a Syringe
Evaporation and Boiling
SCIENTIFIC
Introduction
Water boils at 100°C right? Not always! Baffle your students with this demonstration of water boiling at room temperature.
Concepts
• Vapor pressure
• Phase change Materials (for each demonstration)
Water, tap or deionized
Stopcock
Beakers, borosilicate, 250-mL
Syringe, without needle, 140-mL
Hot plate
Thermometer
Safety Precautions
Be careful when pulling the plunger back. The plunger may snap back very quickly if it is not held tightly. Wash hands thoroughly
with soap and water before leaving the laboratory. Follow all laboratory safety guidelines. Please review current Material Safety Data
Sheets for additional safety, handling, and disposal information.
Preparation
1. In a borosilicate beaker, heat tap water to between 80 and 90°C.
2. Fill a second beaker with warm tap water (between 40 and 50°C).
3. Screw the stopcock onto the syringe.
Procedure
1. Ensure the stopcock is open and fill the syringe with approximately 25 mL of the hot water.
2. Hold the syringe so that the stopcock is up and carefully adjust the volume of the syringe to remove any air bubbles.
3. Close the stopcock.
4. Pull back on the plunger and observe the water.
5. Eject the water from the syringe and repeat the activity with warm tap water.
Disposal
Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures
governing the disposal of laboratory waste. The water may be disposed of down the drain.
Tip
• Experiment with different water temperatures or even different liquids—such as ethyl alcohol.
Discussion
Every liquid boils at the temperature at which its vapor pressure equals the pressure above its surface. By decreasing the
pressure inside the syringe water will boil below 100°C. When the plunger is originally pulled the air pressure in the
syringe falls below the water’s vapor pressure, causing the water to boil. If the plunger is held back long enough, the boiling
© 2016 Flinn Scientific, Inc. All Rights Reserved.
Publication No. 91107
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Boiling in a Syringe continued
slows and eventually stops. As the water boils, the water vapor produced is pressurizing the area above it. The water will
continue to boil until the pressure equals that of the vapor pressure or until there is no liquid left—whichever comes first.
Connecting to the National Standards
This laboratory activity relates to the following National Science Education Standards (1996):
Unifying Concepts and Processes: Grades K–12
Evidence, models, and explanation
Constancy, change, and measurement
Content Standards: Grades 5–8
Content Standard B: Physical Science, properties and changes of properties in matter, motions and forces
Content Standards: Grades 9–12
Content Standard B: Physical Science, structure and properties of matter, motions and forces
Flinn Scientific—Teaching Chemistry™ eLearning Video Series
A video of the Boiling in a Syringe activity, presented by DeWayne Leineman, is available in Evaporation and Boiling, part of the
Flinn Scientific—Teaching Chemistry eLearning Video Series.
Materials for Boiling in a Syringe are available from Flinn Scientific, Inc.
Catalog No.
AP9159
AP6315
AP6049
AP7233
Description
Replacement Poor Man’s Buret Stopcock
Syringe, without Needle, 140-mL
Thermometer, Digital
Hot Plate, Flinn, 49 5 49
Consult your Flinn Scientific Catalog/Reference Manual for current prices.
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© 2016 Flinn Scientific, Inc. All Rights Reserved.