Combined Gas Law

A lab of how pressure, volume, and temperature affect gas


The Combined Gas Law combines Charles Law, Boyle's Law, and Gay Lussac's Law. The Combined Gas Law that a gas pressure x volume x temperature= constant. The Combined Gas Law shows that pressure is inversely proportional to volume, or higher volume equals lower pressure, pressure is directly proportional to temperature, or higher temperature equals higher pressure and volume is directly proportional to temperature, or higher temperature equals higher volume.


How does temperature affect the water and gases inside the cup?

Materials (you will need)

  • candle (make sure it's over 3 inches tall)

  • modeling clay

  • water

  • food coloring

  • glass

  • plate

  • matches/lighter

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Safety Procedure & Equipment

  • Use goggles as you are going to be using a match and liquids.

  • You may use an apron and gloves because the food coloring may stain your clothes and skin.

  • Use caution when lighting the match or find an adult to help you.

  • Report any fires or burns immediately to the teacher or adult.

  • Tie you hair back (because we are using fire and we don't want you to burn your hair off)

  • Roll up baggy sleeves (using fire and don't need burning sleeves)


  1. Have your plate accessible. Grab a small handful of clay and mold it into half a sphere. Place it on the plate.

  2. Put the candle, wick side up, into the middle of the clay.

  3. Mix 3 drops of food coloring (any color) into a cup of water. Stir until it is mixed completely.

  4. Pour the water onto the plate around the clay.

  5. Carefully light the match and light the candle.

  6. Place the glass cup around the clay and the candle so that the cup is face down.

  7. After the candle heats up the air inside the glass, the water should start rising.