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. V

    Kinetic Energy in relation to the ideal gas law

    I'm trying to fit this together. For monotomic molecules, the avg kinetic energy is 3/2 k_b T for diatomic, it is 5/2 k_b T PV = n_particles * k_b T Why is there no factor of 3/2 or 5/2 in the ideal gas law? How is it factored out?
  2. K

    Can Boyle's Law Determine How Far a Submerged Bottle Must Be Sunk?

    My physics teacher recently assigned this challenge and I have no clue where to begin. I think the ideal gas law might apply but I'm not sure. Any insight? A bottle, full of air at atmospheric pressure, whose volume is 500 cubic centimeters, is sunken mouth downwards below the surface of a...
  3. V

    Ideal gas law - work out temperature and pressure

    A neon tube of volume 1.0 × 10−3m3 holds a sample of 3.0 × 1020 atoms of neon gas in equilibrium. The distribution of speeds of the neon atoms shows a peak at 500 m s−1. The neon may be treated as an ideal gas. (Take the mass of each neon atom to be 20 amu.) What is the Temp & Pressure of the...
  4. L

    Thermodynamics Ideal Gas Law problem (pressure problem)

    Homework Statement If 2.00 m³ of a gas initially at STP is placed under a pressure of 5.00 atm, the temperature of the gas rises to 39.0°C. What is the volume? STP means it's at 0°C and 1 atm of Pressure, correct? V1 = 2.00 m³ V2 = ? T1 = 0°C = 273°K (My main confusion was units: °C...
  5. P

    Ideal Gas Law Problem: Balloon Volume Change @ Different Pressures

    Homework Statement You have a balloon (stretchy) filled with one liter of He at 1 atm and 298 Kalvin. The balloon is suddenly placed into a room at .5 atm and 298 Kalvin. What is the temperature of the gas inside the balloon a little while after this happens? Homework Equations P*V=n*R*T...
  6. L

    Ideal gas law hot air balloon problem

    Homework Statement A hot-air balloon achieves its buoyant lift by heating the air inside the balloon, which makes it less dense than the air outside. Suppose the volume of a balloon is 1900 m3 and the required lift is 2500 N (rough estimate of the weight of the equipment and passenger)...
  7. L

    Problem using the ideal gas law

    Homework Statement In an internal combustion engine, air at atmospheric pressure and a temperature of about 20°C is compressed in the cylinder by a piston to 1/4 of its original volume (compression ratio = 4.0). Estimate the temperature of the compressed air, assuming the pressure reaches 20...
  8. S

    Using Ideal Gas Law to find P, V, or T

    Ok, so I'm doing this homework online and I THINK I'm doing it correctly, but I'm getting incorrect answers. Homework Statement 0.290 mol of argon gas is admitted to an evacuated 40.0 cm^3 container at 60.0 degrees C. The gas then undergoes an isochoric heating to a temperature of 300...
  9. L

    Having trouble using the ideal gas law for this problem.

    Homework Statement A pressure as low as 1 * 10^-8 torr can be achieved using an oil diffusion pump. How many molecules are there in 1 cm^3 of a gas at this pressure if its temperature is 371 K?Homework Equations PV = nRT = NkTThe Attempt at a Solution I converted 1*10^-8 torr to atm and got...
  10. T

    How to obtain temperature from a PV vs P diagram using ideal gas law?

    As stated in the question: I have PV(T) [J/kg] vs P [Pa] plotted for 2 different temperatures. I'm to approximate the the temperatures using the lines and the ideal gas law. Note: V is the specific volume. I have no clue how to do this: I know that PV vs P is just as if I had nRT vs P. From...
  11. E

    Find the final temperature? (Ideal Gas Law)

    Homework Statement Find the final temperature? PV relationship -- PV^1.2 = constant P1 = initial pressure = 720 kN/m^2 V1 = initial volume = 0.4 m^3 V2 = final volume = 1.2 m^3 T1 = initial temperature = 225 C I managed to get the final pressure part out of the way but don't know where to...
  12. T

    R is the constant in the ideal gas law.

    Homework Statement i need to derive the ideal gas law Homework Equations this is the equation to end with. PV=NkT The Attempt at a Solution I am not entirely sure where to start with this derivation. I believe Newton laws. where your going to have Fx= Px/t anyone...
  13. C

    Thermodynamics quiz using ideal gas law

    1. Homework Statement T1=300K P1=100kPa V1=1m^3 T1=T2=T3 P2=P3=200kPa V3=0.1m^3 Q: Air initially at 300kpa is contained inside a piston-cylinder device with a volume of 1m^3. The cylinder is equiped with a check valve allowing air to escape when the air pressure reaches 200kPa. An...
  14. S

    Thermodynamics - Ideal Gas Law

    Homework Statement A cylinder contains 2 moles of an ideal monatomic gas that is initially at state A with a volume of 1.0 x 10-2 m3 and a pressure of 4.0 x 105 Pa. The gas is brought isobarically to state B. where the volume is 2.0 x 10-2 m3. The gas is then brought at constant volume...
  15. S

    Ideal Gas Law and dimensional analysis

    Homework Statement The ideal gas law can be recast in terms of the density of a gas. a) Use dimensional analysis to find an expression for the density \rho of a gas in terms of the number of moles n, the volume V, and the molecular weight M in kilograms per mole. b) With the expression...
  16. J

    Calculate Piston Height in Ideal Gas Law Problem | Homework Statement

    Homework Statement A vertical cylinder has a piston of mass "m" on top that is free to move without friction. If there are "n" moles of an ideal gas in the cylinder at absolute temperature "T", what is the height "h" of the piston above the bottom of the cylinder so that it will be in...
  17. J

    Ideal gas law in two dimensions?

    Hi everyone, I know that in P=nRT/v R = 8.314 m3*Pa/mol*k Now, when you are trying to calculate P, if you have volumn in m3 on the bottom, everything cancels out and you are left with Pa. I've just developed a simulator which simulates particle motion over time and calculates...
  18. F

    Truck cylinder, ideal gas law problem

    Homework Statement One cylinder in the diesel engine of a truck has an initial volume of 500 cm^3. Air is admitted to the cylinder at 30 C and a pressure of 1.0 atm. The piston rod then does 450 J of work to rapidly compress the air. What is its final temperature? What is its final volume...
  19. O

    Ideal Gas Mixture Composition Calculation

    Homework Statement A rigid cylinder of 1000cm cubed contains 4.168grams of an ideal gas mixture. The gas mixture consists of methane and ethane at a temperature of 100C and a pressure of 500kPa a) Estimate the average molar mass of the mixure b) Calculate the composition of the mixture on a...
  20. C

    Ideal Gas Law- finding gas density

    Homework Statement What is the density of radon gas at 0 degrees C and 1 atmosphere? Homework Equations PV= nRT 0 C = 273 K density = mass/volume g/m^3 The Attempt at a Solution I want density = g/m^3 Below are the units of PV = nRT. I thought that breaking it down...
  21. S

    Andrew mason ideal gas law and adiabatic expansion problem

    Q1. ADIABATIC FREE EXPANSION(unrestricted and free) in vacuum gas a volume of gas is released expected expansion proceeds withouut change in internal energy therefore temperature is contant (joule's law) . there is no pressure acting on this system threfore no work is done...
  22. F

    Question concerning Ideal Gas Law correction to a teacher & tactons

    Whoops, I meant to say tact. Hehe, maybe tactons are the gauge bosons for the tact force. My Chemistry teacher, who has a Ph.D in Biology., is teaching us that one can use the Celsius temperature scale for the Ideal Gas Law using (approximate) R = 0.0821 \frac{atm * L}{mol * K} . Where R is...
  23. G

    Ideal Gas Law: Solve 1.0x10-6 mmHg @ 40°C

    Homework Statement Current vacuum technology can achieve a pressure of 1.0x10-6 mm of Hg. At this pressure, and at a temperature of 40.0 C, how many molecules are in 1.00cm3 ? [b]2. Homework Equations [/b pv=nrt The Attempt at a Solutioni solved it using the ideal gas equation and...
  24. G

    Ideal Gas Law and a helium tank

    Homework Statement Helium in a steel tank is at 250kPa, 300K with a volume of .1m^3. It is used to fill a balloon. When the pressure drops to 150kPa, the flow of helium stops by itself. If all the helium is still at 300k, how big balloon is produced? Homework Equations I used the ideal...
  25. M

    AP Question involving Ideal Gas Law - Thermal Physics - Pressure

    [SOLVED]AP Question involving Ideal Gas Law - Thermal Physics - Pressure I am having some trouble with an old ap problem(PART C ONLY), see below: Homework Statement 1996 AP PHYSICS B Free Response Question: The inside of the cylindrical can has a cross sectional area of 0.005 m^3 and...
  26. P

    An approximation of the ideal gas law for real gases

    Homework Statement Even at low density, real gases don't quite obey the ideal gas law. A systematic way to account for deviations from ideal behavior is the virial expansion, PV=nRT(1+B(T)/(V/n) + C(T)/(V/n)^2+...) where functions B(T), C(T) and so on are called the virial...
  27. P

    Ideal gas law problem concerning the exponetial atmosphere: part 4

    [b]1. Homework Statement [/b Estimate the pressure , in atmospheres, at the following locations:Odgen Utah(1430 m above seas level);Leadville colorado(3090 m) Mt. Whithney (4420 m) and various other cities above sea level. (assume that the pressure at sea level is 1 atm.)Homework Equations...
  28. S

    How High Can Temperature Go with 10^4 Joules in a Monoatomic Gas Cylinder?

    Homework Statement This is Pathria (2nd Ed) 1.6 and it seemed simple enough but the magnitude of the answer seems unbelievably large: A cylindrical vessel 1 m long and .1 m in diameter is filled with a monoatomic gas at P = 1 atm and T = 300 K. The gas is heated by an electrical discharge...
  29. P

    Ideal gas law problem : part 3

    Homework Statement Assuming that the temperature of the atmosphere is independent of height, solve the barometric equation to obtain the pressure as a function of height: P(z)=P(0)exp(-mgz/kT) Show that the density obeys a similar equation. Homework Equations dP/dz=-mgP/kT...
  30. P

    How do I solve for dP/dz in the ideal gas law using mass and density?

    Homework Statement Calculate the mass of a mole of dry air, which is mixture of N2(78 percent by volume, O2 (21 percent) and argon (1 percent). Use the ideal gas law to write the density of air in terms of pressure, temperature , and the average mass of the air molecules. Show , then...
  31. P

    Ideal gas law concerning the exponential atmosphere

    Homework Statement Consider a horizontal slab of air whose thickness(height) is dz. If this slab is at rest, the pressure holding it up from below must balance both the pressure from above and the weight of the slab. Use this fact to find an expression for Dp/dz, the variation of pressure...
  32. P

    Which room contains the greater mass of air?

    Homework Statement Rooms A and B are the same size and are connected by an open door. Room A however, is warmer(perhaps because its windows face the sun). Which room containks the grater mass of air? explain carefully. Homework Equations PV=nRT, PV=NkT, N=Na*n The Attempt at a...
  33. G

    How Does the Mole/Mass Ratio Affect Pressure Calculations in Turbine Engines?

    What is the mole/ Mass ratio for ambient air at a given Temp/ Humidity? I am trying to get a very rough calculation of a pressure increase in a turbine engine with a given increase in temperature. In the ideal gas law alternative of PV=m/M(RT), The only part of the equation I am having...
  34. G

    Ideal Gas Law and a gas bubble

    Homework Statement A gas bubble with a volume of 0.10 cm^3 is formed at the bottom of a 10.0 cm deep container of mercury. If the temperature is 27C at the bottom of the container and 37C at the top of the container, what is the volume of the bubble just beneath the surface of the mercury...
  35. S

    Ideal Gas Law and kinetic energy

    Homework Statement An empty room in a house near the Atlantic coast has a volume of 45m3. What is the kinetic energy of all of the gas molecules in the room on a 30C summer day? Homework Equations pv = nrt The Attempt at a Solution I realize that this is an ideal gas law problem, but I...
  36. A

    Ideal gas law, applied to non-rigid container

    I'm trying to determine the internal volume of a container using the ideal gas law principle. 1. A container of known volume is pressurized with air to some known value relative to ambient. 2. The container of unknown volume is vented to ambient. 3. Temperature is constant for all air...
  37. S

    Ideal Gas Law - spacing between particles of the gas

    Homework Statement One mole of an ideal gas is a temperature 300K adn at 1.00 atm pressure. a) find the volume. b) Estimate the average spacing between the particles of the gas. Homework Equations For the first part I used PV=nRT and solved for V to determine the volume which I found...
  38. B

    Ideal Gas Law Question: Calculating Final Balloon Volume at High Altitude

    A sealed balloon is filled with 1.00 L of He gas at 23 deg C and 1.00 atm. The balloon rises to a point in the atmosphere where the pressure is 220 torr and the temperature is -31 deg C. What is the final volume of the balloon after it reaches an altitude where the pressure is 220 torr? If...
  39. P

    Ideal Gas Law: Encyclopaedic Experimental Data

    The “ideal gas” law The well-known, encyclopaedic experimental data (about gas compressability factor) show the general trend: the more rarefied gas the more accurate “ideal gas” law, or the same in other terms: the higher vacuum the more accurate “ideal gas” law. 1) Are another...
  40. P

    Ideal gas law - isovolumetric problem

    Homework Statement A gas sample enclosed in a rigid metal container at room temperature (20 C) has an absolute pressure p_1. The container is immersed in hot water until it warms to 40 C. What is the new absolute pressure p_2? Express your answer in terms of p_1 Homework Equations PV = nRT...
  41. B

    Ideal Gas Law (Thermal Physics)

    guys, I'm having difficulty in solving this problem. Two vessels, one having 3 times volume of the other, are connected through narrow tube of negligible volume. The initial temperature is 290K. The small vessel is then cooled down to 250K while the large vessel is heated up to 400K. What is...
  42. N

    Ideal Gas Law and Isobaric Processes

    Hi, So let's take the standard example of a gas in a container with a piston at the top. Charles' Law states that at constant pressure, an increase in temperature (kinetic energy of gas molecules) will increase the volume. This makes sense both conceptually and mathematically (per PV = nRT)...
  43. N

    How Can a Balloon's Volume Increase When Cooled?

    Homework Statement On a warm day 90F, the air in aballon occupies a volume of .25m3 and exerts a pressure of 20 lb/in2. If the baloon is cooled to 30F in a refrigerator, the pressure drops to 14.2lb/in2. What is the volume of the balloon Homework Equations...
  44. K

    Calculating Moles Using the Ideal Gas Law

    Homework Statement When the volume of a gas is 2.81 L, the pressure is 740 Torr and the temperature is 20oC, how many moles of gas is there? Homework Equations PV=nRT The Attempt at a Solution 740 Torr = 740*133.3 = 98.6*10^3 Pa Temperature in Kelvin: 293 K n = PV/RT =...
  45. C

    Beer Bubble Rises: Find Volume Ratio - 65 characters

    A bubble, located 0.200 m beneath the surface in a glass of beer, rises to the top. The air pressure at the top is 1.01 X 10^5 Pa. Assume that the density of beer is the same as that of fresh water. If the temperature and number of moles of CO2 remain constant as the bubble rises, find the ratio...
  46. C

    Calculating Oxygen Volume in Hospital Tanks Using Ideal Gas Law

    Oxygen for hospital patients is kept in special tanks, where the oxgen has a pressure of 65.0 atm and a temp. of 288 K. The tanks are stored in a separate room, and the oxygen is pumped to the patient's room, where it is administered at a pressure of 1.00 atm and a temp. of 297 K. What volume...
  47. O

    What are the limitations of the Ideal Gas Law?

    I've been looking at Charles law, Boyles law, the Pressure law, and the Ideal gas law, PV=nRT. I want to know, what limitations are there to the gas law? Basically, why aren't real gasses ideal, when isn't it possible to use the ideal gas law, and in such a case, what else do you have to use...
  48. G

    Ideal Gas Law & Combined Gas Law Problem

    [SOLVED] Gas laws Homework Statement A balloon containing 2000m^3 of helium gas at 1.00atm and a temperature of 15.0 C rises from ground level to an altitude at which the atmospheric pressure is only 0.900atm. Assume the helium behaves like an ideal gas and the balloon's ascent is too rapid...
  49. E

    Ideal Gas Law: Exploring Independent Variables

    Homework Statement http://ocw.mit.edu/NR/rdonlyres/Physics/8-044Spring-2004/7A20B047-A049-44D6-96D2-75602F179856/0/notes_dfnitns.pdf There it says tht the number of independent variables of a simple fluid is 2 (see the "Complete Specification" section). But the ideal gas law is PV=NkT which...
  50. I

    Ideal Gas Law Application: Finding the Temperature of Air in a Tire

    [SOLVED] Ideal Gas Law Application Homework Statement One Sunday morning a family takes an automobile trip to Grandma's. At the start of the trip, the temperature is 288K (15C), and the gauge pressure in the tires is 32lb/in^2 (psi). (The gauge pressure is the excess over 14.5 psi, the...
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