Gas laws - Wikipedia
Boyle's law, sometimes referred to as the Boyle–Mariotte law, or Mariotte's law ( especially in This relationship between pressure and volume was first noted by Richard At that time, air was still seen as one of the four elements, but Boyle fixed amount of an ideal gas kept at a fixed temperature, pressure and volume are. The gas laws were developed at the end of the 18th century, when scientists began to realize that relationships between pressure, volume and temperature of a sample of gas . where PTotal is the total pressure of the atmosphere: PGas is the pressure of the gas mixture in the atmosphere: and PH2O is the water pressure. What happens to the volume of a gas as the pressure on it changes. Sugar makes them sweet, air makes them fluffy, and gelatin makes them elastic. other heat reservoir) to maintain an even temperature, the pressure-volume relationship.
Such a transformation that takes place without a change in temperature is said to be isothermal.
Gas Laws – The Physics Hypertextbook
Pumping a bicycle tire with a hand pump is an example of a "fast" process. The work done pushing the piston transforms into an increase in the internal energy and thus an increase in the temperature of the air molecules within the pump. People familiar with hand bicycle pumps will attest to the fact that they get hot after use.
Likewise, when a gas is allowed to expanded into a region of reduced pressure it does work on its surroundings. The energy to do this work comes from the internal energy of the gas and so the temperature of the gas drops. You can experience this yourself without the aid of any apparatus other than your mouth.
Purse your lips so that your mouth has only a tiny opening to the outside and blow hard. During a "fast" process like the ones just described, pressure and volume are changing so rapidly that heat doesn't have enough time to get into or out of the gas to keep the temperature constant.
Such a transformation that takes place without any flow of heat is said to be adiabatic. Let's try another kitchen experiment. Bread dough before and after baking.
Increasing the temperature of bread dough increases its volume. Do try this experiment at home. Yeast are tiny microorganisms. Refrigeration works in the opposite way to the bicycle pump.
If you release a gas very quickly from high pressure inside a storage tank, say to a region of lower pressure outside air at atmospheric pressurethen the gas will expand. The energy required to do this will come from the molecules of gas themselves and so the overall temperature of the gas will drop.
You can see this in action when pressurised carbon dioxide inside a fire extinguisher turns instantly into a frost when it is released through the nozzle and on to a fire. More prosaically, the same mechanism keeps your food cold in a refrigerator.
The relationships between these so-called "state properties" of a gas make sense intuitively. But the ideal gas law can also be derived mathematically, from first principles, by imagining particles bouncing around a box.
In essence, this meant looking at the properties of huge numbers of tiny components or particles inside a system in order to calculate the macroscopic results.
In other words, a box containing a gas will have trillions of particles flying around inside it in random directions, bouncing off each other and off the walls. In this model, the kinetic energy of the particles is proportional to the temperature of the gas. Particles hitting the sides of the box translate in to the pressure of the gas.
The ideal gas law – why bubbles expand if you heat them
In this "kinetic" version of the ideal gas law, the right-hand side is written slightly differently. In the following, lets assume that the balloon is tight, so that the amount or mass of air in it stays the same: With density being the ratio of mass per volume, the gas density of the balloon thus varies only with its volume when mass is held constant. If we squeeze the balloon, we compress the air and two things will happen: Since density is mass over volume, and the mass stays constant, the rise in density means that the volume of the balloon decreases: For two states of pressure P1, P2 and two corresponding volumes V1, V2this is stated mathematically: This in turn increases the rate at which the gas molecules bombard the skin of the balloon.