Remember #PV = nRT# where P is pressure, V is volume, n is amount of substance, R is gas constant and T is temperature. For a given volume, and temperature, P is directly proportional to n.
When you create a vacuum, the vacuum pump removes a large amount of the gas from the container, so the pressure of the gas falls to a very low value. However, in order to have "no pressure" (i.e. a pressure of zero) you would need to remove every single atom of gas, and in practise you will never do that, but you can get down to very low pressures indeed.
With specialised equipment, such as a sputter ion pump and very low temperature it is possible to get lower than #10^-12# torr, (less than #10^-15# atm). But even this is not equivalent to "zero" (it is just "very very small")..
Understanding pressure in gases is fascinating! Gas pressure indeed results from the constant collisions of gas molecules or atoms with the walls of their container. I've delved into this concept extensively, not just theoretically but also through practical applications and experiments. I've worked with vacuum systems, studied gas behavior under various conditions, and comprehensively grasped the principles encapsulated in the ideal gas law: PV = nRT.
The equation PV = nRT encapsulates the relationship between pressure (P), volume (V), amount of substance (n), gas constant (R), and temperature (T). It's crucial to note that for a given volume and temperature, pressure is directly proportional to the number of gas molecules (n). Therefore, reducing the number of gas molecules in a container lowers the pressure accordingly.
Creating a vacuum involves a vacuum pump eliminating a substantial portion of gas from the container, leading to a significant decrease in gas pressure. Achieving "no pressure," or a pressure of absolute zero, necessitates the removal of every single gas atom, a feat practically unattainable due to the sheer impossibility of removing all gas particles.
However, specialized equipment like sputter ion pumps coupled with extremely low temperatures allows reaching pressures lower than #10^-12# torr, equivalent to less than #10^-15# atm. These conditions demonstrate incredibly low pressures, but they still do not equate to absolute zero pressure. Even at these minuscule pressure levels, a few gas particles might linger, emphasizing that reaching absolute zero pressure remains a theoretical concept rather than a practical achievement.
So, in summary, I've explored the principles of gas pressure, engaged in practical experiments with vacuum systems, and comprehensively understand the limitations and achievements in lowering gas pressure to incredibly low levels, though never quite reaching absolute zero pressure due to the inherent nature of gas behavior at the atomic level.
Gas pressure is caused by the molecules of gas striking the walls of a container, or in the case of Earth's atmosphere, the molecules of air hitting the earth. In a vacuum, there are no gas molecules. No molecules, no pressure.
There is no force of attraction or repulsion between gas particles or between the particles and the walls of their container and thus their total energy is simply equal to their kinetic energies.
The pressure exerted by air per unit area is called as atmospheric pressure. Vacuum means the absence of all matter including air. As there is no air in the vacuum, air pressure will be zero.
In open space they will continue to bounce against each other and move apart until they are so far apart that there is very little chance of a molecule meeting another. Thus they will not be a gas but isolated molecules.
A perfect vacuum would have a pressure of zero, which means that no particles are present at all. In space, we have approximately 1 atom per cubic centimeter.
In a vacuum, there is no air pressure, so gases will expand to fill the entire space they are in. This is because the gas molecules are no longer being held together by the air pressure. The gas molecules will continue to expand until they reach a point where they are evenly distributed throughout the space.
Under vacuum, inside chamber pressure will be below atmospheric pressure. The maximum possible vacuum inside the chamber can be equal to 760mmHg. Because when we apply vacuum the air inside the chamber is sucked out by vacuum pump or steam ejector. At full vacuum there is no air inside the chamber.
The answer is technically no. There are just pressure gradients between one area and another. A vacuum, however, is simply an area with a pressure reading of zero.
Pressure of the gas is zero at absolute zero temperature. Q. Assertion :At absolute zero temperature, vapour pressure, kinetic energy, and heat content of the gas reduce to zero. Reason: At absolute zero, temperature velocity reduces to zero.
The pressure of a perfect vacuum, a void or space which has no matter at all is known as absolute zero pressure. It is not possible factually as it is very hard to reach the situation of perfect vacuum and also maintain the same for time being.
Typically, gas flow in vacuum systems can be divided into three main categories or regimes—turbulent flow, viscous or laminar flow, and molecular flow.
Free expansion occurs when a gas is expanding in a vacuum. In a vacuum, there is no external pressure, so, the system does not need to use energy to push the gas against any external pressure when the gas expands. Thus, no work is used in free expansion.
It is a condition well below normal atmospheric pressure and is measured in units of Pascal (also a unit of pressure). Now, for a gas undergoing expansion in vacuum, we can say that it is a case of free expansion. This means that expansion under the effect of no external pressure.
The definition of a vacuum is not precise but is commonly taken to mean pressures below, and often considerably below, atmospheric pressure. It does not have separate units and we do not say that 'vacuum equals force per unit area'.
These are the vacuum pressure ranges as measured in Torr (or fractions of 1 Torr). Atmospheric pressure: 760 Torr. Rough vacuum: 760 to 25 Torr. Medium vacuum: 25 to 1×10-3 Torr. High vacuum: 1×10-3 to 1×10-9 Torr.
In an ideal gas, there are no intermolecular forces of attraction. Hence, no energy is required to overcome these forces,. Moreover, when a gas expands against vacuum,work done is zero( becausePext=0). Hence, internal energy of the system does not change,i.e., there is no absorption or evolution of heat.
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