The Relationship of Temeprature and Pressure

Most everything in existence is affected by a change in temperature and pressure. My partner and I will not be testing everything in existence, we will only be testing how a gas is affected by changes in these two properties of matter while in a closed system. There already exists an idealized line graph of how a gas should react when these two properties are changed,but that graph is only for an ideal gas that follows Boyle's law to the letter. The properties of an ideal gas are represented well by this graph
Since these graphs only represent an idealized gas, no known gas when subjected to changes in temperature or pressure and those changes recorded on a similar graph would model such a clear graph


If the temperature of a gas in a closed system is increased, then the pressure would increase an equal amount.


Temperature and pressure are directly proportional to each other. The higher the temperature, the higher the pressure. When you increase the temperature of a gas, the speed of its molecules will increase as well. This leads to the molecules impacting against each other more often and hitting the container more often, which, by its very definition, is an increase in pressure. This is known as Gay-Lussac’s law. We can often see Gay-Lussac’s law in action the hotter months of the year, during summer if a tire explodes it could be because with the increase of temperature the pressure inside of the tire also increases beyond the capacity of the tire, thus causing it to explode. Another example of Gay-Lussac’s is soda. When a can of soda that is cold is opened it fizzes much less than a warm can, because there is more pressure inside the warm can. A final example for Gay-Lussac would be if someone is scraping the ice off of a road or drive way, if that person drives over the ice or parks there car on the ice for a minute the pressure on the ice would increase and warm that area of the ground making it easier to remove.[1] [2]

Another law that is closely related to Gay-Lussac’s Law is Charle’s law. The law states that when the pressure of a gas is constant the gas will expand (volume) with how much the temperature of the gas is increased. An example for Charle’s law is very similar to Gay-Lussac becasue they are so smiliar, but if you go out on a cold day the pressure in your tires is less than they would be in a warmer temperature. [3]

Robert Boyle was a chemist, inventor, philosopher and physicist. Robert Boyle was born in the Irish county of Waterford,on the 25Th of January, 1627 . He was the fourteenth child and seventh son. When he was 10 his dad, Richard, hired a private tutor for his son In 1614 Robert went to Italy and met a very old Galileo. When he finally returned home he was very interested in science, by this time his father had passed on. He studied at oxford periodically, and later in his eventful life with the help of Robert Hooke they improved on Otto Von Guericke's air-pump and made the “Pneumatical Engine”. Robert then proceeded to conduct several experiments on the properties of air, and after these experiments he came to the conclusion of his first law. The pressure and volume of a gas are inversely proportional, at a constant temperature. Boyle’s law is commonly seen in nature with bubbles. The deeper in the sea we go the more the pressure around us increases, and as bubbles rise to the surface the pressure decreases so the volume increases and the bubbles get bigger the higher they go.[4] [5]

Both Boyle’s law and Gay-Lussac’s law both require a closed system to function properly. A closed system is defined as a system able to transfer heat and energy with its surroundings, but not matter. An enclosed system is useful for our purposes because we are testing relationships between pressure and temperature. In our experiment the transfer of heat from the enclosed system we used did not affect our experiment in a detrimental fashion because the temperature of the air we used was only the independent variable. Plus we had a Bunsen burner under it. The pressure cooker we used as an enclosed system was perfect for our uses as it did not allow gas to escape, our dependant variable was the pressure of the air in the pressure cooker. Even though our pressure cooker did have use it’s pressure release valve, it was airtight until a certain number of atmospheres inside it was reached.


The barometer is used to measure atmospheric pressure, but there exists smaller versions for more specific experiments. Evangelista Torricelli is normally associated with creating the barometer in 1643, but history also suggests that an Italian mathematician, Gasparo Berti, made the first water barometer without realizing it in 1640. If we would not had the pressure cooker at our disposal we would have needed to use some sort of barometer to measure the pressure[6]

A thermometer is an instrument that is used to measure a change in temperature. There are regularly two parts to a thermometer, for example with the classic mercury thermometer there was the “temperature sensor” or the bulb at the bottom, and also it needs a way to show the change in temperature the thermometer does this with a long neck that the mercury would rise up in to show the current temperature. It is unsure who created the first thermometer, but several people are credited for it such as Galileo, and Sanitori.[7]


Our planned procedure started out as it should with us equipping our safety gear, we used safety goggles. The next thing we did was find and set up a Bunsen burner. Using a match given to us by Mr. Carpenter, the Bunsen burner was lit. A proper flame has no orange in it and two cones,the outer a light blue color and the inner a darker blue color. The reason for this is because a flame with two blue cones is more fuel efficient then a flame with any orange coloring in any of it’s cones. A properly set flame on a Bunsen burner has a temperature hotter than 500 degrees Fahrenheit, the hottest part of the flame is located at the tip of the inner darker blue cone. Because of this, the Bunsen burner was placed on a glass tile. After this, Mr. Bowie, our physics teacher, checked the connections between the pressure cooker and the laptop we used to record our data. The pressure cooker had two wires running from it to the laptop. One wire linked the computer to the thermometer, and the other wire with the plastic tubing linked the computer to the absolute pressure sensor in the pressure cooker. After this, Mr. Bowie started the recording process on his computer to see if his laptop was working properly, Mr. Bowie then showed us how to control his laptop. After everything was in order we lit our Bunsen burner and waited for data to roll in. After a short time we noticed water starting to condense on the outside of the pressure cooker so we extinguished the Bunsen burner and asked Mr. Bowie about it. Mr. Bowie explained that the water on the outside was not leaking from the inside, because the lead was not sealed properly. After this we waited for the lid cool down, took it off and resealed it, and checked everything then lit up our Bunsen burner again and restarted our experiment. We did not wait until the water in the pressure cooker was back down to background temperature. We let the Bunsen burner add heat to the water until the overflow valve on the pressure cooker started to release steam. Once this had occurred we turned off the Bunsen burner and let the pressure cooker and the water in it cool off. Because Mr. Bowie set up the pressure cooker, we left the tear down to him.

Overall the project was a success. Aside from the minor mishap where the pressure cooker was leaking, everything went out without a problem. The experiment supported our hypothesis, which was: If the pressure of a gas is increased, then the temperature of the gas will increase with it as long as the gas remains in a container of constant size. As a whole the experiment went as we expected to, I would have been very surprised if the temperature of the gas did not increase as its pressure was increased.



  1. ^ Gas Laws
  2. ^ Gay-Lussac
  3. ^ Gas Laws
  4. ^ Robert Boyle, Stanford Encyclopedia of Philisophy
  5. ^ Gas Laws
  6. ^ Barometer,
  7. ^ Thermometer,