Condensation & Carbonation: Why Do Cold Drinks Sweat?

Learning Objectives

Students will:

  • Observe how condensation forms on the outside of cold containers.
  • Compare condensation on two different liquids (water vs. soda).
  • Learn how carbonation and insulating bubbles affect temperature transfer.
  • Practice scientific skills: predicting, observing, recording data, and explaining results.
  • Understand how temperature differences create condensation.

Materials

  • 2 regular drinking glasses (not insulated)
  • Ice cubes (same amount for both glasses)
  • Room-temperature water
  • Room-temperature carbonated soda
  • Paper towels
  • Scissors
  • Timer or stopwatch (optional)
  • Data sheet or science notebook

Preparation

  • Make sure both liquids are room temperature before starting.
  • Place both glasses on a table or flat surface where they will not be disturbed.

Procedure

1. Set Up Both Glasses

  • Put the same number of ice cubes in each glass.
  • Pour water into one glass, soda into the other.
  • Allow soda foam to settle until both liquid levels match.

2. Observe & Wait

  • Watch both glasses for a few minutes.
  • As the outside of the glasses cool, condensation will begin to form.
  • Have students predict which glass will “sweat” more.

3. Compare Condensation

  • Cut two equal squares of paper towel.
  • When condensation appears, wipe the outside of each glass with a different paper towel.
  • Compare how wet each square becomes.

4. Ask: Which one had more condensation?

Students should notice:

  • The ice water glass produces noticeably more condensation.
  • The soda glass stays a little drier.

Scientific Explanation

Even though the water and soda started at the same temperature:

Water Glass → More Condensation

  • Cold water directly cools the glass surface.
  • A colder glass surface attracts more moisture from the air.
  • More moisture = more condensation.

Soda Glass → Less Condensation

Inside the soda:

  • Carbon dioxide bubbles attach to the inside walls of the glass.
  • These bubbles act like a thin insulating layer.
  • The glass surface doesn’t get as cold because the bubbles block heat transfer.
  • A warmer surface attracts less moisture, so less condensation forms.

This is a small but observable difference — perfect for budding scientists!

Vocabulary

  • Condensation – water droplets that form when warm air touches a colder surface
  • Carbonation – the carbon dioxide gas dissolved in soda
  • Insulation – something that slows down heat transfer
  • Temperature – how hot or cold something is

Optional Data Collection

Create a simple chart:

Time (minutes) Condensation on Water Glass Condensation on Soda Glass
2 minutes light / medium / heavy light / medium / heavy
4 minutes
6 minutes

Older grades can measure:

  • Mass of paper towels (weighed before and after)
  • Surface temperature of the glasses with thermometers

Extensions by Grade Level

Grades 1–2

  • Draw pictures showing which glass had more “sweat.”
  • Sort vocabulary cards (hot, cold, condensation, bubble).

Grades 3–5

  • Write a simple explanation:
    “The bubbles acted like insulation because…”
  • Predict what would happen if you used juice, seltzer, or sports drinks.

Grades 6–8

  • Explore heat transfer more deeply: conduction, convection, insulation.
  • Use digital thermometers to track glass temperature changes over time.
  • Compare carbonated vs. flat soda.
  • Discuss real-world examples (insulated mugs, double-walled cups).

Clean Up

When finished:

  • Enjoy the soda and water!
  • Wipe the table dry.
  • Recycle paper towels if appropriate.

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