# Demonstrating Gas Laws

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• Published : March 16, 2013

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EXERCISE 10
Demonstrating Gas Laws Lab
Group II

Introduction
The three gas laws discover the relationship of pressure, temperature, volume, and amount of gas. Boyle's Law tells us that the volume of gas increases as the pressure decreases. Charles' Law tells us that the volume of gas increases as the temperature increases. A third gas law may be derived as a corollary to Boyle's and Charles' laws. According to Gay-Lussac's Law, for a given amount of gas held at constant volume, the pressure is proportional to the absolute temperature. Methodology

* Materials
We will need several materials for the three demonstrations of gas laws. For Part 1, the Cartesian Diver, we will need a bottle with cap, and a medicine dropper. For Part 2, the Rising Water Experiment, a birthday candle, food coloring, matches, a shallow dish, petroleum jelly and an Erlenmeyer flask. For the last experiment, the Invisible Giant, we will need a pair of beaker tongs, a hot plate, an empty aluminum soda can, a beaker of ice water and some ice. * Procedure

Part 1: The Cartesian Diver
First, fill the bottle to the very brim with water. Drop the medicine dropper with the bulb up and close the bottle tightly. The medicine dropper should float in the water. Squeeze the bottle gently and record your observations. Stop squeezing the bottle and again, record your observations. Part 2: Happy Birthday

First, put a small glob of petroleum jelly in the center of the shallow dish. Then, stand a birthday candle upright in the petroleum jelly. Don’t use a lot of extra petroleum jelly or the demonstration won’t work properly. Add 1 – 2 centimeters of water to the dish. Add a drop or two of food coloring. Light the birthday candle. Lastly, place the Erlenmeyer flask mouth down over the candle. Stand it up right in the dish over the candle. Record your observations. Part 3: The Invisible Giant

Add a little bit of water to the empty soda can. Place the soda can on the hot plate and turn on the hot plate. While the water in the can is heating up, fill the dish about ¾ full of ice water. When the water in the can has reached a boil, quickly use the beaker tongs to move it from the hot plate and place it mouth down into the ice water. Record your observations. Data and Observations:

Part 1: The Cartesian Diver
In the bottle's uncompressed state, the medicine dropper floats. When the walls of the bottle are squeezed, the medicine dropper sinks.
Part 2: Happy Birthday
When the flask is placed over a burning candle in a plate of water, the water level rises significantly when the candle burns out.
Part 3: The Invisible Giant
After heating, the soda can was place upside down into the water. The soda can implodes and was crushed instantaneously. Conclusions:
Part 1: The Cartesian Diver
1. An object floats in water when it is less dense than water. 2. Why does the dropper initially float in the water?
* The diver originally floats because the dropper contains part air and part water. Air is less dense than water, thus the medicine dropper is initially lighter or less dense than water. 3. What happens to the volume of the air trapped in the dropper when you squeeze the bottle? * When squeezed, water is forced up into the dropper bulb and compresses the air in it. 4. If the air in the dropper contract, what happens to its density? * If the air in the dropper contracts, its density increases. 5. Explain why the dropper sinks when you squeeze the bottle? * When the bottle is squeezed, the pressure increases inside the bottle.  This added pressure decreases the volume of the gas in the bottle, including the gas in the medicine dropper.  This demonstrates Boyle's Law.  When the volume of the gas inside the medicine dropper decreases, the space left behind is filled with water.  As a result, the mass inside the medicine dropper has increased substantially, but the volume has remained the same.  More mass...