What is Ideal gas law: Definition and 238 Discussions

The ideal gas law, also called the general gas equation, is the equation of state of a hypothetical ideal gas. It is a good approximation of the behavior of many gases under many conditions, although it has several limitations. It was first stated by Benoît Paul Émile Clapeyron in 1834 as a combination of the empirical Boyle's law, Charles's law, Avogadro's law, and Gay-Lussac's law. The ideal gas law is often written in an empirical form:




P
V
=
n
R
T


{\displaystyle PV=nRT}
where



P


{\displaystyle P}
,



V


{\displaystyle V}
and



T


{\displaystyle T}
are the pressure, volume and temperature;



n


{\displaystyle n}
is the amount of substance; and



R


{\displaystyle R}
is the ideal gas constant. It is the same for all gases.
It can also be derived from the microscopic kinetic theory, as was achieved (apparently independently) by August Krönig in 1856 and Rudolf Clausius in 1857.

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  1. A

    How Does Compressing a Syringe Affect an Ideal Gas?

    Homework Statement if you have an ideal gas in a syinge, then you compress the syringe to a point, then that means that Volume has decreased. Consequentally, Pressure must increase to compensate (oin order for PV=nRT to be true) right? I think this is wrong but I am not undersnating why...
  2. E

    Ideal Gas Law Chang ein VolumeProblem

    I am having a little trouble on this problem: Can I treat this as an Isobaric expansion and an Isothermal compression? I think I found the change in Volume like this: \frac{\Delta V}{V_{0}}=\beta\Delta T How do I find the Pressure?
  3. L

    Enviro Chem.- simple ideal gas law calculation.

    Homework Statement 1. Ozone has a maximum concentration of 4.7 x 1012 molecules/ cm3 at an altitude of 20 km. The total pressure at this altitude is 100 torr. Using the ideal gas law, what is the mole fraction of O3 at that altitude? Now express the mole fraction in ppb. Homework...
  4. I

    Inelastic collision and ideal gas law

    I am not even sure if my question itself is correct. According to ideal gas law, all the collisions for a gas molecules are elastic in nature. Now, suppose a hydrogen atom collides with a neutron (assuming 1-D motion for simplicity), will i consider that collision to be elastic always, or are...
  5. M

    Ideal Gas Law: Calculating Pressure and Moles of Helium Gas

    ideal gas law...I think... Homework Statement Useful Constants: 1 Torr = 133.32 Pa; R = 8.3145 J/mol·K You have a thin metal sphere of unknown volume that contains helium gas at low pressure. You put the entire metal sphere into a bath of liquid nitrogen, and a pressure gauge on the...
  6. J

    Ideal gas law and moles of air

    [SOLVED] Ideal gas law Please help. I don't know what to do. The air temperature and pressure in a laboratory are 23°C and 1.2 atm. A 1.67 L container is open to the air. The container is then sealed and placed in a bath of boiling water. After reaching thermal equilibrium, the container is...
  7. J

    Solving the ideal gas law for volume -> length

    [SOLVED] solving the ideal gas law for volume --> length Consider an ideal gas at 27.0 degrees Celsius and 1.00 atmosphere pressure. Imagine the molecules to be uniformly spaced, with each molecule at the center of a small cube. What is the length L of an edge of each small cube if...
  8. J

    Calculating Ideal Gas Volume with the Ideal Gas Law

    Consider an ideal gas at 27.0 degrees Celsius and 1.00 atmosphere pressure. Imagine the molecules to be uniformly spaced, with each molecule at the center of a small cube. What is the length L of an edge of each small cube if adjacent cubes touch but don't overlap? ______________ I know...
  9. J

    Solving the ideal gas law for moles

    Suppose Gabor, a scuba diver, is at a depth of 15 m. Assume that: 1. The air pressure in his air tract is the same as the net water pressure at this depth. This prevents water from coming in through his nose. 2. The temperature of the air is constant (body temperature). 3. The air acts...
  10. C

    Why Does the Ideal Gas Law Fail at the Critical Point of Carbon Tetrachloride?

    [SOLVED] ideal gas law numerically If I calculate the pressure of water vapor at stp (in mmHg), P= 1000*7.502e-3*R*(0+273)*.804/18; where the 7.502e-3 factor converts from Pa to mmHg, 1000 is because my density (.804) is in grams/cm^3, 18 is the molar mass of water, etc etc. and this comes out...
  11. T

    Calculating Gas Temperature Change Using the Ideal Gas Law

    Homework Statement A gas at 293.15 degrees kelvin and atmospheric pressure is compressed to a volume one fifteenth as large as its original volume and absolute pressure of 3000kPa. What is the new temperature of the gas? Homework Equations p1v1/t1=p2v2/t2 The Attempt at a Solution...
  12. S

    Which Gas Behaves Most Ideally: N2, CO, or H2?

    Homework Statement In general, which of the following gases would you expect to behave the most ideally? a) N_2 b) CO c) H_2 Homework Equations N/A The Attempt at a Solution Okay, so I know that CO would definitely not behave the most ideally. I tried looking this up on the...
  13. R

    Calculating Volume for 1 kg of O2 at 150,000 Pa and 100K using Ideal Gas Law

    Homework Statement I need to find the volume for 1 kg of diatomic oxygen for a pressure of 150,000 Pa and a temperature of 100K. This is really part of a larger project, and I need to make sure I'm not tripping up on little details. It's that 1 kg of diatomic oxygen that I am a bit unsure...
  14. H

    Ideal Gas Law for concave objects

    This is much longer than the normal post, so please bear with me. I was wondering if anyone here knows the complete derivation of Ideal Gas Law (or can recommend a book that describes it clearly and fully), who can tell me whether its conclusions are valid for any shape of gas particle, and...
  15. M

    Problem with ideal gas law and a spring Help please

    Problem with ideal gas law and a spring! Help please! Homework Statement We have a box divided in two parts by a piston without friction, and in one part there are n moles of an ideal gas and a Spring orf constant K and natural longitude L which keeps the piston in equilibrium. According to...
  16. D

    Questions about the ideal gas law - thermodynamics

    im studying building systems engineering technology. yeh i know it's only a technology program at the cegep level but when I'm done with it, I'm going to do software engineering in university. anyways I'm having trouble to understand two problems in the book. if anyone can help me with this, it...
  17. P

    Ideal Gas Law: Low Pressure Application

    Hi every body, We are taught in school that the gas law : pv=nRT can not be applied at high pressure, say a hundred atm. Now I just think of the fact that can we use that equation at very low pressure? Several mTorr for example. Thanks
  18. J

    Solve Ideal Gas Law Problem: V2 and P2 for Ar and N2 mixture at 400 K

    1. A rigid tank contains .5 kmol of Ar and 2kmol of N2 at 250 kPa and 280 K. The mixture is now heated to 400 K. Determine the volume of the tank and the final pressure of the mixture. 2. PV=NRT Can you find the initial volume by using PV=NRT? V=NRT/P V=(2.5)(8.314)(280)/250=23.2...
  19. C

    Ideal gas law + Newton's 2nd law problem

    Homework Statement A cylinder has its lid connected to a spring with k = 2000 N/m. The cylinder is filled with 5.00 L of gas witht he spring relaxed at a pressure of 1.00 atm and a temperature of 20.0C. (a) If the lid has a cross-sectional area of 0.0100 m2 and negligible mass, how high will...
  20. T

    Ideal Gas Law + 1st Law of Thermodynamics

    Hi everyone ^^! I hope you had a great holiday season. I have a homework problem that I'm a little confused on. I will provide my answers/work as usual, and would like it if someone could check my work, or tell me if an explanation is wrong/needs more information. My teacher would like us to be...
  21. C

    Ideal Gas Law Helium balloon Problem

    Ideal Gas Law Problem :) Homework Statement A balloon is filled with helium at a pressure of 1.0 x 10^5 Pa. The balloon is at a temperature of 23°C and has a radius of 0.13 m. (a) How many helium atoms are contained in the balloon? (b) Suppose we increase the number of helium atoms in...
  22. M

    Ideal Gas Law Lab: Finding R with PV = nRT

    For the first part of my lab, I have a graph with pressure(atm) as a function of temperature(K). For the second part of my lab, I have a graph with pressure(atm) as a function of inverse volume(mL^-1) For both of these, i am supposed to find the value for R, the gas constant. So far far...
  23. B

    Solve Ideal Gas Law Problem: 1.2L Bottle of SO2 at 78PSI, 23°C

    In preparation for a demonstration, your professor brings a 1.2 L bottle of sulfur dioxide into the lecture hall before class to allow the gas to reach room temperature. If the pressure gauge reads 78 psi and the lecture hall is 23°C, how many moles of sulfur dioxide are in the bottle? (Hint...
  24. quasar987

    When to apply the ideal gas law PV=nRT

    Is the formula only applicable during quasi-static processes? In other words, is it only true for a gaz at equilibrium?
  25. W

    Understanding the Ideal Gas Law: State Changes and Work Calculation | Geocities

    The diagram below shows state changes of an ideal gas. The temperature of states (1), (2), (3) are T_1[K], T_2[K] and T_3[K] respectively. The state change from (1) to (2) is an adiabatic change (not an isothermal change). The state change from (2) to (3) is a change at constant pressure...
  26. K

    Question about the ideal gas law

    Hi, I have a question about the ideal gas law. I have been under the impression that if volume goes down then pressure and temperature go up. But, if you look at the equation T=PV/nR, it seems that if volume, say, doubles, pressure will be halved and vice-versa. While that makes sense, it...
  27. A

    Ideal Gas Law Car TIre Problem

    here's another one that stumped me An automobile tire is inflated with air originally at 10C and normal atmospheric pressure. During the process the air is compressed to 28% of its original volume and the temperature is increased to 40C. a) what is the tire pressure? b) after the car is...
  28. S

    Why Does My Ideal Gas Law Calculation Differ from the Textbook?

    hello all. I'm trying to figure out this problem and it's bugging me because it's soooo simple yet i keep getting the wrong answer. here's the problem: If 1.00 mol of carbon dioxide gas at 350 K is confined to a volume of 400 cubic centimeters, find the pressure of the gas using the...
  29. C

    Calculating Spacing Using Ideal Gas Law

    Here's the question: For what temperatures are the atoms in an ideal gas at pressure P quantum mechanical? Hint: Use the idea gas law PV = N k_B T to deduce the interatomic spacing. Answer: T < \left( \frac{1}_{k_B} \right) \left( \frac{h^2}_{3m} \right)^{\left(...
  30. A

    Calculating the Final Temp of an XK8 Cylinder Using the Ideal Gas Law

    A Jaguar XK8 convertible has an eight-cylinder engine. At the beginning of its compression stroke, one of the cylinders contains 499cm^3 of air at atmospheric pressure (1.01×105 Pa and a temperature of 27.0 C. At the end of the stroke, the air has been compressed to a volume of 46.2 cm^3 and the...
  31. S

    Scuba Diving and Ideal Gas Law

    Pressure, volume, and temperature of the air in the diver's lungs when the last underwater breath is taken as p1,V1 , and T1, respectively. Pressure, volume, and temperature of the air in the diver's lungs when the surface is reached to be p2, V2, and , T2 respectively. Salt water has an...
  32. D

    Ideal gas law problems: Pascals vs Atms?

    Hi group, Simple arithmetic problems using PV = nRT or NkT. How do you know when to use pressure units in atmospheres or pascals? For example, in 1 particular problem they give you a pressure in units of Torr, volume in cubic cm and temp in Kelvin and ask for the number of molecules. Couldn't...
  33. M

    How Does the Ideal Gas Law Apply to Changing Conditions in a Gas System?

    Problem1. A cylinder with a movable piston contains gas at a temperature of 42 degrees Celicius, with a volume of 40m^3 and a pressure of 0.233*10^5 Pa. What will be the final temperature of the gas if it is compressed to 0.728 m^3 and its pressure is increaded to 0.609*10^5 Pa? Answer in K...
  34. M

    How Does the Ideal Gas Law Solve Temperature and Volume Changes in Gases?

    Problem1. A cylinder with a movable piston contains gas at a temperature of 42 degrees Celicius, with a volume of 40m^3 and a pressure of 0.233*10^5 Pa. What will be the final temperature of the gas if it is compressed to 0.728 m^3 and its pressure is increaded to 0.609*10^5 Pa? Answer in K...
  35. S

    Ideal gas law constant R conversion

    Hi, not sure if this is the right forum to ask this in, but I was trying to convert the ideal gas law constant R (from PV = nRT) from: 8.31 (Pa * cu. meters) / (mol * Kelvin) to the equivalent: 10.73 (psia * cu. ft) / (lb. * mol * Rankine) Here's the conversion factors I've been using...
  36. X

    Solving Ideal Gas Law: Find Final Volume of Helium

    Given: R=8.31451 J/(K*mol) Two moles of helium gas initially at 187 K and 0.33 atm are compressed isothermally to 0.57 atm. Find the final volume of the gas. Assume the helium to behave as an ideal gas. Answer in units of m^3. I've tried this many many times and i keep getting 5.455...
  37. V

    Ideal Gas Law and Balloon Volume

    Hey guy, I didnt think i would ever have to deal with gas laws after i got out of AP chem, but it has showed up again in physics. Tell me what to do. Suppose the volume of a balloon decreases so that the temperature of the balloon decreases from 280K to 240K and its pressure drops from...
  38. Alethia

    How Does Changing Gas Quantity and Temperature Affect Pressure?

    Hi, I'm having some trouble doing my homework for Physics. I would appreciate it if anybody would help me or lead me in the right direction. Thank you. 1. Gas is confined in a tank at a pressure of 1.0x18^8 Pa and a temperature of 15.0 degrees Celcius. If half the gas is withdrawm and the...
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