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:

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.