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. S

    How Does Compression Affect Temperature in Ideal Gas Laws?

    Perhaps I have some mental block with basic algebra (so don't judge me on that), but... Here is a simple high-school level question regarding ideal gas laws: If I have two fixed chambers "a" and "b", both of equal volume connected in the middle with a compressor, and I compress gas taken...
  2. T

    Using Ideal Gas Law and Charles Law to compute limit

    Homework Statement The ideal gas law from chem is PV = nRT. A process carried out at const. pressure is said to be isobaric. A process carried out at const. temperature is said to be isothermal. A.) Using limits and the ideal gas law and assuming const. number of moles, show that that the...
  3. A

    Q) What is the final temperature of the compressed air in degrees Celsius?

    [b]1.A Jaguar XK8 convertible has an eight-cylinder engine. At the beginning of its compression stroke, one of the cylinders contains 493cm^3 of air at atmospheric pressure (1.01*10^5 Pa) and a temperature of 27.0 degress celcius . At the end of the stroke, the air has been compressed to a...
  4. N

    Very hard ideal gas law problem

    Homework Statement A cylinder of height H = 1.2 m high rests on a table. The bottom half of the cylinder is filled with an ideal gas; on top of that is a frictionless, movable disk of negligible mass and thickness. Above the disk, the top half of the cylinder is completely filled with liquid...
  5. K

    Ideal gas law, What stands for P

    the ideal gas law, PV=nRT, I have question about the parameter P. Does P stands for the pressure exert by the gas or the atmospheric pressure? Say helium gases are enclosed inside a balloon. Then it gives pressure, temperature, and volume data to use the gas law. Does the pressure refer...
  6. D

    Question including ideal gas law, change in energy/work.

    Homework Statement This question would be impossible to solve without the diagram, which I can't post so instead i'll just tell you what I have so far. gas springs are commonly used on trunk lids of cars. They are a closed system consisting of a pressure tube and piston rod with piston...
  7. N

    [fluid dynamics] are they trying to use the ideal gas law for LIQUIDS?

    In my course they're using the equality U = \frac{p}{\alpha \rho} with alpha some constant (U = internal energy per mass, p = pressure, rho = density). They explicitly derive it for an ideal gas yet later apply it to a liquid (in the context of deriving the Navier-Stokes energy equation). Seems...
  8. C

    Reciprocity theorem and ideal gas law

    what is the reciprocity theorem? and does ideal gas law PV=nRT follows the theorem?
  9. B

    Solving Ideal Gas Law Problem: Volume of Rigid Container at 1.20 atm and 60.0°C

    Homework Statement A rigid container holds 2.80 mol of gas at a pressure of 1.20 atm and a temperature of 60.0 degrees Celsius. What is the container's volume? Homework Equations PV=nRT The Attempt at a Solution (2.80*8.31*333)/1.20 = 6457m^3 This answer seems way too big...
  10. M

    Ideal Gas Law with spring, no numbers, closed container

    Homework Statement The closed cylinder of the figure has a tight-fitting but frictionless piston of mass M. the piston is in equilibrium when the left chamber has pressure p0 and length L0 while the spring on the right is compressed by ΔL. a. What is ΔL in terms of p0, L0, A, M, and k...
  11. Z

    Detemining the mass of water vapour in air (Ideal gas law)

    1. I am supposed to calculate the mass of water vapour in one cubic meter of air that has a relative humidity of 80% at 20°C. 2. p[v] = (eM[w]) / (RT) Where: p[v] = vapour density e = water vapour pressure M[w] = molar mass of water R = gas constant (8,314 J / (mol*K)...
  12. J

    Ideal Gas Law and pressure in a holder

    Homework Statement What is the pressure inside a $50.0$ L container holding $105.0$ kg of argon gas at $20^\circ$ C?Homework Equations Ideal Gas Law: PV=nRTThe Attempt at a Solution From the ideal gas law, I get P=\frac{nRT}{V}=\frac{\frac{105.0\times 10^3g}{36g/mol}\times 0.08214\frac{L\cdot...
  13. B

    How much steam is needed to open a relief valve using the ideal gas law?

    I am trying to solve a problem but I am not sure if I am going about it the right way. I am using the ideal gas law to find out the amount of steam it will take to open a relief valve. Using the law I have calculated the amount of steam that will be in a volume but I am not sure if that is also...
  14. C

    Ideal Gas law and mole conversions

    Homework Statement You have several identical balloons. You experimentally determine that a balloon will break if its volume exceeds 0.900L . The pressure of the gas inside the balloon equals air pressure (1.00 atm). The air inside the balloon has a constant temperature of 22 C. How many...
  15. C

    How Does Temperature Constancy Affect Atmospheric Pressure with Altitude?

    Ideal Gas Law Problem (Please help!) Show that if the temperature in the atmosphere is independent of altitude, then the pressure as a function of altitude y is p=(p initial)e^(-mgt/kT) Where m is the average mass per molecule of air. I really have no idea where to start. Please help...
  16. M

    Ideal Gas Law Gas in a Piston Problem

    Homework Statement A gas is in a piston which is at 25 degrees celsius with a volume 4.0L is held in a room at atmospheric pressure. If the temperature is increased to 193 degrees celsius, the piston expands to it's maximum volume. If the pressure in the room is then increased to 4.3 atm, what...
  17. M

    How Many Molecules in 1 mL of a Vacuum at 27.0 degrees Celsius?

    Homework Statement A vacuum pump on Earth can produce a vacuum with a pressure as low as 1.00*10^-8 torr. How many molecules are present in each mL at a temperature of 27.0 degrees Celsius? V = 1mL = 10^-3 L <-- How many sig figs should I use here? Should I make it 1.00*10^-3L or keep it...
  18. M

    Can you write the ideal gas law this way?

    Homework Statement Calculate the work done in an adiabatic process where P1 = 1.2 atm, V1 = 0.2 m^3, P2 = 2.4 atm and V2 = 0.117 m^3 Homework Equations W=-nCvΔT PV=nRT The Attempt at a Solution I tried to group the work formula as follows: W=-(nΔT)Cv and then tried to rewrite...
  19. P

    How Do You Calculate the Mass of Oxygen in a Cylinder Using the Ideal Gas Law?

    Homework Statement A fixed mass of oxygen (O2, molecular mass = 32 g/mol) is contained in a cylinder whose volume is 2.80 liters. The pressure is 148 atm when the temperature is 23oC. Find the mass of oxygen in the cylinder. a. 20 g b. 80 g c. 140 g d. 280 g e. 546 g Homework...
  20. P

    What Volume Does One Mole of Ideal Gas Occupy at 300 K and 1 atm?

    Homework Statement What is the volume of one mole of ideal gas at 300 K and at standard atmospheric pressure? a. 23.2 L b. 24.1 L c. 24.6 L d. 25.7 L Homework Equations PV=nRT The Attempt at a Solution 1atm*V=1mole*8.314*300K V=2494 L which is not in the options :s...
  21. B

    Ideal Gas Law Problem: Solving Pressure & Bottle Purge

    Homework Statement A wine-dispensing system uses argon canisters to pressurize and preserve wine in a bottle. An argon canister for the system has a volume of 55.0 mL and contains 26.0 g of argon. Assuming ideal gas behavior, what is the pressure in the canister at 295 K? When the argon is...
  22. B

    Ideal Gas Law - Differential Approximation due to variable increase in %.

    Homework Statement This is a problem form my calculus book, which states: According to the ideal gas law, the pressure, temperature, and volume of a confined gas are related by P=kT/V, where K is a constant. Use differentials to approximate the percentage change in pressure if the temperature...
  23. D

    Volume of 1 Mole Gas at 1atm, 273.15K

    What volume does 1 mole of gas occupy at 1 atm pressure and 273.15K? PV = nRT so V =nRT/P V = (1)(8.314)(273.15)/1 Im getting 2270.96, the answer is ment to be 22.4L, what am i doing wrong? P= 1 V= ? n= 1 R= 8314 T= 273.15K
  24. B

    Water + Water Vapor - Can I use ideal gas law?

    Homework Statement Sealed container which is used to heat 200 kg water is initially at 25 degrees C. Since the container is sealed, the water remains in saturated state while its temperature and pressure increases. The remaining volume of the container is filled with water vapor at the same...
  25. M

    Similar Ideal Gas Law question

    Homework Statement A 500 m^3 tank is filled with saturated liquid-vapor mixture of water at 200 kPa. If 20% percent of mass is liquid and 80 percent of the mass is vapor, the total mass in the tank is? Homework Equations pV=mRT The Attempt at a Solution Don't have a clue... sorry
  26. M

    Calculating Final Temperature Using Ideal Gas Law | Homework Help

    Homework Statement A rigid tank contains 5 kg of an ideal gas at 4 atm and T=40 deg C. Now, a valve is opened and half of the mass of the gas is allowed to escape. If the final pressure in the tank is 1.5 atm, the final temperature in the tank is? Homework Equations pV=mRT The...
  27. Y

    Calculating Carbon Fixation: Ideal Gas Law for Forests | 25oC & 1 atm

    Homework Statement Each square meter of an actively growing forsest fixes on average each year 1 kg of carbon from the atmosphere into plant matter through photosynthesis. The atmosphere is approximately 20% O2 and 80% N2, but contains 0.046% CO2 by weight. a.) What volume of air at 25oC...
  28. P

    Venturi tube obeys ideal gas law?

    The ideal gas law staes that pressure is inversely proportional to volume. Makes sense but I am confused by what happens in a venturi tube, where volume seems to decrease at the same time that pressure decreases also. I understand that dynamic pressure increases in the throat but what am I...
  29. A

    Trying to understand weather balloons better (ideal gas law)

    Here's my understanding... (P1V1)/T1 = (P2V2)/T2 P1 = starting pressure, typically sea level pressure which is 1atm. V1 = Starting volume of the gas inside your balloon. T1 = starting temperature, temperature at ground level. P2 = final pressure, this should be the pressure at your flight...
  30. P

    Ideal Gas law Partial derivative

    This is a question from my calculus book that i thought was interesting, its not homework but I am curious to how you go about showing it. Show T (∂P/∂T)(∂V/∂T)=NR We know PV=NRT so if we take a partial how does the T end up on the other side?
  31. S

    Chemistry Ideal gas law, concentrations, mole fractions

    I haven't been able to try all parts of this question yet as I've been running into problems fairly near the start. I've asked for help with it but have just been told 'use the ideal gas law' which is what I tried to do but can't seem to get it right. We have been given answers to parts a, b...
  32. L

    Absolute Temperature and the Ideal Gas Law

    Homework Statement A cylinder in a car engine takes Vi = 4.50 x 10^-2 m^3 of air into the chamber at 30°C and at atmospheric pressure. The piston then compresses the air to one-ninth of the original volume (0.111Vi) and to 20.0 times the original pressure (20.0 Pi). What is the new...
  33. K

    Ideal Gas Law Change Rate Problem

    Homework Statement The gas law for an ideal gas at absolute temperature T (in kelvins), pressure P (in atmospheres), and volume V (in liters) is PV = nRT, where n is the number of moles of the gas and R = 0.0821 is the gas constant. Suppose that, at a certain instant, P = 9.0 atm and is...
  34. P

    How does the ideal gas law work?

    So here's what has me all confuzzled about the relationship between temperature and pressure: Temperature is proportionate to average kinetic energy... but why does expanding a container lower the KEavg of the container's gaseous contents? Shouldn't the conservation of momentum keep all the...
  35. R

    What is the Correct Calculation for Pressure in Boyle's Ideal Gas Law Problem?

    Homework Statement A 3-Litre Vessal gas at a pressure of 200 kPa. 5-Litres of gas at the same pressure if forced into the vessal. Calculate the new Pressure Homework Equations P1V1+P2V2 The Attempt at a Solution P1=200*V1=3 / V2=5 = P2 120 kPa New Pressure = 120 kPa I am...
  36. P

    Ideal Gas Law, Pressure equilibrium

    Ok so I just need help with clarifying in how I should attempt to solve this problem. There's two question involving the same information. I've solved the first question but need help with setting up the second one. Here is the problem: Two containers, A and B are filled with argon. The...
  37. P

    How Many Air Molecules are Contained in a Smooth Cylinder at Equilibrium?

    Homework Statement A smooth, well-greased insulated cylindrical container with a metal base has a light (so you can neglect its weight), airtight piston that can frictionlessly move up and down the inside of the container. A mass M = 73 kg sits on top of the piston. The piston has a circular...
  38. L

    Ideal gas law and a bicycle pump

    Homework Statement When you push down on the handle of a bicycle pump, a piston in the pump cylinder compresses the air inside the cylinder. When the pressure in the cylinder is greater than the pressure inside the inner tube to which the pump is attached, air begins to flow from the pump to...
  39. A

    Simple Ideal Gas Law but i keep getting it wrong

    Homework Statement P=1.5 atm; n=2 mols, R=8.314; T=250 K; V=? Homework Equations PV=nRT i converted p into Pa and got 151987.5 Pa. The Attempt at a Solution I plugged in all of the numbers and got V=0.027 L but it keeps saying my answer is wrong. It says answer for 2 sig figs. I...
  40. T

    Derive the ideal gas law from Charles', Boyle's, and Avogadro's, how?

    What is the trick to derive the ideal gas law and gas constant from the "combination" of Charles', Boyle's, and Avogado's laws? The general chemistry books I have seen tell me this is how they derived the ideal gas law and constant but they do not show how that is achieved. I tried to go about...
  41. K

    What is the Ideal Gas Law in Space?

    Homework Statement A nebula-a region of the galaxy where new stars are forming-contains a very tenuous gas with 100 atoms/cm^3. This gas is heated to 7500 K by ultraviolet radiation from nearby stars. Put the answer in atmospheres. Homework Equations pV=nRT R=8.31 n=N/NA NA =...
  42. A

    Hot air balloon - Ideal gas law

    Homework Statement Estimate the required temperature of the air inside a (rigid) balloon in order for it to achieve lift off. Volume 2000m3 \summass, mtot=920kg Homework Equations pV=NkT p=\frac{Force}{Area} \rho=\frac{m}{V} The Attempt at a Solution We require Fup>(mair+mtot)g (assume...
  43. F

    Ideal gas law problem in outer space

    Homework Statement In outer space, the density of matter is about one atom per cm^3, mainly hydrogen atoms, and the temperature is about 3.4K. Calculate the average speed of the hydrogen atoms, and the pressure (in atmospheres) M_H = 1.0079au = 1.67 X 10^-27 Kg 1 Hydrogen atom per cm^3...
  44. mishima

    Can gas pressure and density be reduced without changing temperature?

    I'm curious from a lab sort of perspective, how does one keep a gas at a constant temperature yet decrease both pressure and density? Like how could I reduce the pressure of argon gas with the gas kept at room temperature? Put it in a vacuum larger than the space it normally occupies or...
  45. W

    Ideal Gas law and a hot air balloon problem

    My physics problem is as following, Estimate the average temperature of the air inside a hot air balloon. Assume that the total mass of the unfilled balloon and payload is 500kg. what is the mass of the air inside the balloon? we are told to use a radius of 15m Equations needed density = m/V...
  46. E

    Which unit of pressure is used in the ideal gas law?

    The ideal gas law states that pressure (P) is equal to the product of density (N), the ideal gas constant (R) and temperature (T): P = N x R x T I can't figure out which unit the pressure is actually in, although it does seems to work out as the figure I'm supposed to get with a 11706.85°...
  47. T

    Pressure Cooker-Involving Ideal Gas law and Total Pressure

    Homework Statement A cook puts 9.00g of water in a 2.00L pressure cooker and warms it to 500 degree celcius. What is the pressure inside the container.Homework Equations P_{total} = P_{1} + P_{2} +... (eqn1) PV = nRT (eqn2) \frac{P_{1}}{T_{1}} = \frac{P_{2}}{T_{1}} (eqn3) The Attempt at a...
  48. A

    Ideal gas law practical application

    Homework Statement To measure how far below the ocean surface a bird dives to catch a fish, a scientist uses a method originated by Lord Kelvin. He dusts the interiors of plastic tubes with powdered sugar and then seals one end of each tube. He captures the bird at nighttime in its nest and...
  49. L

    Ideal Gas Law Problem - Environmental Physics

    Homework Statement 1. Consider ideal gas in a rigid cylinder of 2 litres, at pressure of 3 Bar. The gas is connected through a thin capillary to a free expanding bag, which contains ideal gas at pressure 1Bar and volume of 1 litre. A valve in the capillary initially prevents the gases to mix...
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