# What is Gas law: Definition and 275 Discussions

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 could be obtained which would hold to approximation for all gases.

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1. ### Chemistry Question about Gas Law Problem

PV=nRT P*1L = 6 moles * 0.0821*298 (I added up all the moles and solved for pressure) P =146.79 atm 146.79 atm * V = 2 moles Ar * 0.0821* 298 (I plugged in the moles for argon and solved for volume) V= 0.333 L Answer key says the answer is 1 Liter. Where did I go wrong?
2. ### Why must we use absolute temperature for the Ideal Gas Law?

For this problem, The solution is, However, why must we use absolute temperature for the ideal gas law (i.e why can we not use Celsius for T) Many thanks!
3. ### Gas law problem (changing volume, temperature and pressure)

I can’t quite work my head around this question, I am having a difficult time analyzing the question, I can’t seem to make out what the initial and final conditions are would appreciate all the help I could get cheers
4. ### Ideal gas law- Find the pressure

Question: Answer: In the third last line of working, I do not understand why the pressure variable is changing? Shouldn't pressure remain constant and only the Volume change?
5. ### Thermodynamics problem (ideal gas law, kinetic theory, processes, etc.)

It is a long problem, but it is simple to understand. I am having trouble with part A. My attempt: Pressure outside > pressure inside container. pV = constant (isothermal). At equilibrium, all gases are at atmospheric pressure. Because it is quasi-static, the pressures of both compartments are...
6. ### Chemistry Ideal gas law problem with two cylinders

my answer will be ##P_1=2 P_2## but I have some doubts, if that is correct or not
7. ### (Dry) Volume Ideal Gas Law Calculation

If the question was asking for (dry) volume, how would you do that?
8. ### Ideal gas law problem -- Pneumatic piston movement with air temperature changes

I have come up with the change in height as 170 cm. My professor does not want to solve for the problem for a reason I do not understand. 170 cm is not part of the answer key. The answer according to the answer key is 65 cm. My attempt is: Initial temperature: p=F/A; (50 *9.8) / (pi * 0.05^2)...
9. ### How is the Ideal Gas Law Derived from Temperature and Pressure Relationships?

I figured that T' is a common factor for both relationships and from there deduceted that T'=p2xt1/p1=v1xt2/v2. However, I don't understand how that can be further manipulated to PV=KT.
10. ### Proof question related to the Ideal Gas Law

A cylinder contains an initial volume V1 = 1m^^3 of a perfect gas at initial pressure p1 = 1 bar, confined by a piston that is held in place by a spring. The gas is heated until its volume is doubled and the final pressure is 5 bar. Assuming that the mass of the piston is negligible and that the...
11. ### Chemistry Ideal Gas Law and Partial Pressures

I had already found the Mass of the product (C3H3N) produced by this reaction (theoretical mass at 100% yield) in a previous problem. I did this by finding the Limiting Reagent (C3H6) in the reaction , calculating the number of moles of C3H6 and using the Molar Ratios in the balanced reaction...
12. ### Chemistry Calculating Mass Percentage of N2H4 in Hydrogen/Nitrogen Mixtures

So essentially you are supposed to find the mass percentage of N2H4 in the Hydrogen/Nitrogen mixtures. The way I understood it, the only way to find the mass percentage of the gasses is to find the mole percentage. Which I got as 25%, based on the fact that the ratio of product gasses to...
13. ### Ideal Gas Law: Question about a compressor exam question

This is a question in my midterm. I calculated for the answer as c) 11.7 atm by the Ideal Gas Law. The professor states that "all the air is originally at 1 atm" in the prompt indicates an idea of "both 70 L of air and existing 6 L of air in the tank are at 1 atm", and he grades d) 12.7 atm as...
14. ### Combined Gas Law: Find Volume V2

P1= 13.6 V1= 1.1 T1= 22 P2 = 14.4 V2= x T2 = 32 my answer is 1.51L am i missing something?
15. ### Ideal Gas Law in Two Dimensions

I am creating a two-dimensional model of an ideal gas, and I was wondering how I should determine initial velocity. Ideally, I would like for the simulation to reach a point where the velocity distribution resembles that of the maxwell-boltzmann curve — will this be achieved if I, say, assign...
16. ### Calculations using the Ideal Gas Law

2.1 * 10^-4m/3 Temperature 310K Pressure: 5.3 * 105 Pa So the Ideal gas formula is PV = nRT 2.1*10^-4m^3 Times 5.3*105Pa = n * Gas Constant * Temperature 2.1*10^-4m^3 (*) 5.3*105Pa = # of moles * I'm not sure what I was doing, but the whole equation stuff got hard and I stopped. I left...
17. ### Gas Law - increasing temperature with constant volume held

I've set up a simple experiment to look at the ideal gas laws. My experiment is relatively simple in that I have a metal tube which is capped on one side. I am then pressurising the tube with air to 100 psi and locking it off. My thought is that as the pressure increased, with volume held...
18. ### Find Vol 2 in Ideal Gas Law Problem with V1 and V2 Open and V3 Shut

Please refer to diagram. V1 is open initially then V2 is open for 5 minutes for pressure to equalize. V1 and V2 are then shut. V3 is opened. What is Vol 2 ? P(final)*V(final) = n(final)* R*T => (Vol1 + Vol2) = n(final)*R*25C/ 0.070 Torr where n(final) = n(Vol1) + n(Vol2) If I shut V3, I...
19. ### Thermodynamics and ideal gas law concepts

I'm having trouble wrapping my head around some thermodynamics and ideal gas law concepts. I don't have a specific textbook question but Just a concept I'm having trouble with. What I'm struggling with is understanding some of the relations between pressure, volume and temperature...
20. ### B Confused about the ideal gas law

Ok, i am struggling to figure something out. I don't know why math is so much easier than physics haha. ok, here is my struggle. I have two states, state 1 and 2, which i will call just 1 and 2. 1: T=298kelvin V=0.025m(cubed) P=310Kpa Mass1=Mass2 R=0.2870 2: T=323kelvin V=0.025m(cubed) P=...
21. ### Exploring the Ideal Gas Law: A Balloon Problem

Homework Statement Homework Equations Ideal gas law The Attempt at a Solution The solution to this problem assumes the pressure inside the balloon is the same as the outside pressure, i.e. atmospheric pressure. Is this a valid assumption? I would guess otherwise.
22. ### What would be a real-life example of the ideal gas law?

Homework Statement What is a real-life example of the ideal gas law? Homework Equations PV = nRT (Pressure x volume = number of moles x the gas constant x temperature in Kelvin) The Attempt at a Solution https://www.reference.com/science/ideal-gas-law-used-everyday-life-3dacbd6ebd3b5949...
23. ### Ideal Gas Law and Pressure at 80°C

Homework Statement An ideal gas has a molar mass of 40 g and a density of 1.2 kg m-3 at 80°C. What is its pressure at that temperature? Homework Equations PV=nRT R constant= 8.314 n= number of moles T= tempreture in kelvin density=Mass/ Volume The Attempt at a Solution i simply solved it like...
24. ### Superheated vapors and Gay-Lussac's Gas Law

I attend a trade school, majoring in HVAC (Heating, Ventilation, and Air-Conditioning). My instructor has given me information that seemingly contradicts what my textbooks tell me about Charles' Law. My instructor is not a scientist. I asked my instructor to reconcile the two seemingly...
25. ### Basic physics units problems involving the Ideal Gas Law

Homework Statement The following is the equation of ideal gas law, where p is pressure (Force/Area), V is volume, n is number of moles and T is temperature in Kelvin. What is the fundamental unit of R? pV = nRT A. kg^−1 · m^−2 · s^ 2 · K · mol B. kg^−1 · m^−4 · s ^2 · K · mol C. kg · m^4 · s...
26. ### Using Ideal Gas Law to Calculate Vertical Pressure Gradient

Homework Statement Consider a cylindrical parcel of air of area A and infinitesimal height dz. If this air parcel is to remain stationary, the difference between the total pressure forces exerted on its top and bottom faces must be equal to its weight. Use this information and the ideal gas...
27. ### I Application of the ideal gas law

Hi, I want to calculate the amount of liquid nitrogen (at boiling temp.) needed to build a pressure of 10.1 bar in a vessel of volume 66 m3. The liquid will be poured slowly into the vessel, boil off and fill the volume with gas at the specified pressure. I make the assumption that the process...
28. ### Thermodynamics: Ideal Gas Law, find the temperature

Homework Statement A 3-ft^3 container is filled with 2-lbm of oxygen at a pressure of 80 psia. What is the temperature of the oxygen?Homework Equations pV= nRT T= PV/nR R= 10.7316 psia x ft^3/ lbmol x R The Attempt at a Solution Hi everyone! So I understand how to use the Ideal Gas Law but my...
29. ### Why does the gas with the smallest molar mass have the highest pressure?

Homework Statement If equal masses of Xenon, Argon and Neon are placed in separate flasks of equal volume and same temperature, which one of the following statements is correct: a) The pressure of Neon flask is greatest. b) The pressure of Argon flask is greatest. c) The pressure of Xenon flask...
30. M

### Ideal Gas Law Homework: Calculating Number Density and Spacing Between Molecules

Homework Statement Consider an ideal gas at 25.0 degrees Celsius and with a pressure of 1.00 atm. a) What is the "number density" of the molecules, expressed as molecules per unit volume? (Cubic meter, cubic centimeter or liter) b) What is the typical spacing between molecules in the gas? Of...
31. ### What is the Ideal Gas Law for a Two-Bulb System with Varying Temperatures?

1. Two equal glass bulbs are connected by a narrow tube and the whole is initially filled with a gas at a temperature of T0 and pressure of P0. Then, one of the bulbs is immersed in a bath at a temperature, T1 and the other in a bath at a different temperature, T2. Show that in this problem, the...
32. ### Ideal Gas Law -- Isobaric Epansion followed by....

Homework Statement An ideal gas with Cv = 5/2R, and γ = 1.4 starts at a volume of 1.5m3 , a pressure of 2.0×105Pa, and a temperature of 300K. It undergoes an isobaric expansion until the volume is V , then undergoes an adiabatic expansion until the volume is 6.0m3 , and finally undergoes an...
33. ### Pressure and temperature of expanding humid air

As a follow-on to this thread, which in turn followed this closed thread, I'm starting a new thread on a related real-world problem. Say I have a 2-liter plastic soda bottle filled partway with water, and pressurized. It has been sitting inverted (with the opening pointed down, and sealed) for...
34. ### I Introducing two identical containers with different gasses

If you have two different containers filled with two different gasses at the same temperature, would they have less pressure when connected to each other? Dalton's law states that each of the gases behave independently when it comes to pressure as they fill the space as if they were the only gas...
35. ### Understanding the Different Forms of the Ideal Gas Law and Their Applications

Hey I was hoping someone could be me a succinct method of knowing what form of the Ideal gas law I need to use and in particular the different R's associated with each form. Form my Thermodynamics class we use PV = nRT Pv = RT PV = mRT Little v being the specific volume (which changes the R...
36. ### I Ideal Gas Law and Differentiation

Is it possible to calculate the rate of change of n with respect to rate of change of Pressure and rate of change of Temperature with V unknown but constant by PV = nRT? Rate of change of Pressure and rate of change of temperature can be measured. R and V are constants.
37. ### What are the units for the Universal Gas Constant?

Homework Statement Hello, I am not asking for the answer to an example, rather how the book got some numbers. The problem is an example from the book and shows me the solution but does not show the steps. Given: The compressed air tank has a volume of .84 ft^3. The temperature is 70 F and the...
38. ### Calculating Hydrogen Mass from Ideal Gas Law

Homework Statement (introduction course of university physics) A 25- L container holds ideal hydrogen (H2) gas at a gauge pressure of 0.25 atm and a temperature of 0°C. What mass of hydrogen gas is in this container? The ATOMIC mass of hydrogen is 1.0 g/mol, the ideal gas constant is R =...
39. ### Gas Law applying to air vs water vapor

Say we have a tire filled with air (equal to ambient air surrounding it in every way). pressure on the gauge is 0. Then, we pressurize it to 1 ATM (15psi). If we heat the tire , the air will be heated and expand based on gas law, or is there a factor that changes it based on the air's...
40. ### Calculating exerted pressure ( gas law lab)

Homework Statement Mass =0.908kg Area= 5.3 x 10^-4 m^2 2. Attempt This was for a lab I am doing on gas laws. Its asking to calculate exerted pressure in kPa. This is what I've done so far : F= 0.908kg * 9.8m/s^2 = 8.8984N Pressure = Force/ Area Pressure= ( 8.8984N) /( 5.3 * 10^-4...
41. ### Question about the derivation of the Ideal Gas Law

I'm an undergraduate taking a physical chemistry course, and I got to a part in my reading about the derivation of the ideal gas law. The passage is linked below...
42. ### Ideal gas law, Find the Temperature of the container?

Homework Statement [/B] There is a lid on a .25m diameter, .30m tall cylindrical container enclosing .021kg of air. The lid is held in place solely by atmospheric pressure. It take 220N of force to pull of the lid at an atmospheric pressure of 101kPa. What is the Temperature of the enclosed...
43. ### I Ideal Gas Law - Real Life Question?

Hi Guys and Gals, As I was pumping up a flat bike tyre, a weird thought occurred to me about the application of the ideal gas law. Once the tyre essentially finds its physical dimension limitations (i.e. is shaped like a bike tyre and no longer changing shapes) and starts putting in reasonable...
44. ### Enthalpy and the Ideal Gas Law: Understanding Constant Pressure Reactions

Hi! I'm new to the forums and currently reading about Chemical Thermodynamics. So here's what I know: ΔE = q - w So for constant volume reactions, no work is done hence: ΔE = q But for constant pressure reactions, heat be may released (for exothermic reactions) and work is done hence: ΔE =...
45. ### Do Different Volumes of Helium Affect Molecular Speed in Balloons?

Homework Statement [/B] Two balloons with Helium gas are filled, first with 10 liters of He and second with 20 liters. Molecules of which balloon will be moving faster as compared to the other? Homework EquationsThe Attempt at a Solution Speed of molecules is directly proportional to...
46. ### Help with Thermodynamics and Gas Law

THE PROBLEM: A steam engine's boiler completely converts 2638 g of water at 83.7 °C to steam at 195.4 °C. The steam, at a constant pressure of 3.28 Pa, expands by pushing a piston of radius 9.4 cm a distance of 8.3 cm. What is the change in internal energy of the water-steam system? MY WORK...
47. ### Ideal Gas Law: What is the new pressure based on factors?

My daughter has the following homework problem we need assistance in confirming if we've understood and completed correctly. Homework Statement The Volume goes from 2.00 Liters to 7.00 Liters, the temperature changes from 800 kelvin to 150 kelvin, and the number moles of gas is quadrupled on...
48. ### Application of Gas Law at super-low volume

When we discuss about Gas Law : [Charles Law, Boyle Law and Gay Lussac Law ] are they still applicable at super low volume and temperature. At such conditions, the gases would undergo phase transition and convert to solid. So will the Gas Laws still be applicable at that stage??
49. ### Ideal Gas Law in "alternate" universe

Homework Statement Assume that in an alternate universe, the laws of physics are very different from ours and that "ideal" gases behave as follows: (i) At constant temperature, pressure is inversely proportional to the square of the volume. (ii) At constant pressure, the volume varies directly...
50. ### Solving Ideal Gas Law Model Homework

Homework Statement My problem is with the last line of the derivation. Usually, we take the rate of change of momentum (force) to be change of momentum divided by the impact time. But this slide of pp showed that the traveling time of the particle in the box is used but not the impact time. Why...