How to Apply Gas Laws to Cooking
Gases are low density materials that have no defined shape or volume, filling each container they are in by expanding equally in all directions. In this manner, gases will exert pressure on all sides of a container. While this may seem an obvious connection, it wasn't always. Scientists spent many years working out the connection between pressure, volume and temperature as they relate to gases. These studies were the foundation for the development of what are now known as the gas laws. These laws can be applied to all gases as they will respond similarly to a variety of conditions.
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Instructions
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Write the following on the white board, "PV = nRT". This is known as The Ideal Gas law. All other gas laws are derivatives of this. The Ideal Gas law basically states that pressure of a gas multiplied by the volume of the gas is equal to the number of mols times the universal gas constant (0.08206 L x atm / mol x K) times the temperature.
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Write the following beneath The Ideal Gas Law, "P1/T1 = P2/T2". This is the third gas law and is used to explain the relationship between pressure and temperature where the volume is fixed or rigid.
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3
Place a small amount of popcorn into an air popper. Turn the air popper on and wait.
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4
Explain the use of popcorn while you are waiting for the kernels to pop. Each kernel of popcorn contains a small amount of water inside and the hard exterior of the corn kernel acts as a container of fixed volume. As the heat is from the surrounding air passes through the kernel casing, the water inside gets warmer. According to The Third Gas Law, an increase in temperature leads to an increase in pressure.
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Catch the popped kernels in a bowl placed beneath the spout of the popcorn popper. When the small amount of liquid water is transformed via heat energy into steam, the gas version of water, the vapor should then respond according to the gas laws. As the kernel continues to take on heat, the pressure of the gas continues to increase, until the kernel finally pops.
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