Boyles Law Apparatus
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Abstract
The objective of this lab was to determine the relationship (if any), between the pressure and volume of a gas given the temperature and # of molecules remained constant. Using the Boyles law apparatus, and textbooks to demonstrate pressure it was concluded that there was a relationship between pressure and volume. However, the relationship was not a direct relationship, and it was determined that the pressure and volume of a gas are inversely proportioned. Thus,proving Boyles theory correct.
Introduction
Objectives: The main objective of this lab was to determine the relationship between the volume and pressure when the temperature and number of molecules remains the same throughout. Other minor objectives of this lab were to determine any possible source of error, so there is more awareness of these errors when conducting another experiment.
Theory: Gases are matter with no definite volume or shape. They will take on the volume and shape of whatever they are being contained in. There are three gas laws. The first is Boyles Law. Boyles law states that at a maintained temperature, and number of molecules, the volume and pressure of a gas are inversely proportional to each other. Which simply means that the higher the pressure is on a gas, the lower the volume of the gas will be, and vice-versa. The formula for this law is: Pâ„-Vâ„-=PІVІ. Vâ„- is the old volume, and Pâ„- is the old pressure. VІ is the new volume and PІ is the old pressure. The second gas law is Charles Law. Charles Law states that there is a direct relationship between volume & temperature(K). As Volume increases, so does Temperature, by the same ratio. The third gas law is the Combined Law. The combined law deals with any combination of Pressure, Volume and temperature. The combined law states that Pressure and Temperature are directly proportioned. Pâ„-Vâ„- Over Tâ„- = PІVІ Over TІ.
The Kinetic Theory of Gases states that:
1) A gas is composed of particles that are in continuous random motion.
2) There is a transfer of energy between colliding particles, but no energy is lost.
3) The volume of gas particles is almost non-significant in comparison with the volume of space they are in. There is much space between particles.
4) Gas particles are considered as having no force of attraction for each other.
This Kinetic theory applies to all ideal gases. Real gases however are different because in a real gas, the volume of gas particles is significant, and gas particles do have some volume. (Opposite of law #3.) In a real gas, the gas particles do have a force of attraction. (Opposite of law #4.)
Robert Boyle was born in 1627, at Lismore Castle, Munster, Ireland as the fourteenth child to the Earl of Cork. He was schooled all throughout Europe, and later went on to attend Oxford. Boyle conducted many experiments throughout his time at Oxford. His greatest contribution is his theory which has come to be known as Boyles Law. This has become the basis for all modern sciences.
Charles law explains how hot-air balloons work. Since a gas will expand when it is heated, the weight of the hot air will occupy a larger volume than cold air of the same weight. This shows that hot air is less denser than the cold air. So, once the air in the balloon gets hot enough, the weight of the balloon plus the hot air will be less than the same volume of cold air, and in turn will make the balloon rise. When the gas in the balloon cools, the balloon will start to lower back down to the ground.
Combined Law just shows how both pressure and volume are directly related to temperature.
Hypotheses: The volume of the air will decrease. Because as increased pressure is applied, the molecules will move closer together causing the volume of the gas to decrease.
Methods
Materials: The materials used in this lab were the Boyles Law apparatus, and textbooks.
Procedure:
1 – Carefully insert the cylinder into the yellow stopper with the needle pointing down. Insert this structure, needle down into the larger wooden block. Dont insert the yellow stopper so far that the wooden block cant rest stably on the lab bench. Place the smaller wooden block on top of the apparatus.
1. 2 – Remove the pin cover from the graduated cylinder and press down or pull up until the plunger reaches 30mL (cm3). Replace the pin TIGHTLY. Test the plunger by pressing down on the small wooden block to make sure that when you let go, it always returns to about 30 mL.
(29 Ð is ok and some experimental error. ) This is volume at 0 textbooks (tbs) of pressure. Add 2.4 tbs of pressure to account for the atmosphere and record your data.
3 – Add one textbook to the center of the small wood platform and record the new volume of the air that is occupying the cylinder. Record the pressure always adding 2.4 tbs to how many tbs used to account for the atmosphere. If necessary, gently hold the book in place.
4 – Repeat step 3 except now with 2 textbooks, and then 3 textbooks, and finally 4 textbooks.
5 – Start the experiment over from step 2 so that you can obtain more trials. Do the experiment a total of 4 times for each textbook load. Average your results for each textbook load.
Results
Table #1:
Trial