# What is Gas laws: Definition and 77 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. ### I Obtaining this form for molar energy under virial expansion (Callen)

In his Chapter 13.3 (2nd edition), Callen gives the standard form for the virial expansion for the mechanical equation of state of a fluid as an exapnsion in powers of the molar volume ##v##: P = \frac{RT}{v}\left(1 + \frac{B(T)}{v} + \frac{C(T)}{v^2} + \dots \right) \equiv P_{ideal} +...
2. ### Applying Dalton's Law: From Popcorn Launchers to Innovative Products

Summary: TL;DR: Doing an assignment in which we are to apply Dalton's Law to a product to improve/ better it OR create a completely new product using the law. Let your creativity run wild! Hi there! I am doing an assignment in which we are to apply Dalton's Law to a product to improve/ better...
3. ### Gas Laws - pumped tires exploding at the top of a mountain

When you pump a bicycle tire before riding up a mountain, the tires may explode. I think it is because of Boyle's law, where since the external pressure decreases, the volume of the tire is supposed to increase and it explodes. The solution says that as the air in the tire expands on heating...
4. ### Calculating the Length of a Water Column in a Beaker

Homework Statement a Basin contains water , a beaker is put upside down to a depth of 3m inside it , if the volume of the beaker is 250 cm^3 . and its C.S area = 200 cm2 calculate the length of the water column which rises inside the baker , supposed that their is no air leakage from the...
5. ### B Could steam be expanded through a nozzle to get 0°C gas?

Obviously expanding the gas cools it down. I'm interested if you could boil water and then expand the high pressure steam to cool it down to 0°C. Or are there subtler thermodynamics that would prevent this?
6. ### I Regarding Joule's gas expansion experiment

Hi, Joule's original gas expansion experiment is often presented like in the following link: http://demonstrations.wolfram.com/JouleExperimentOnFreeExpansion/ The apparent lack of temperature change in this experiment is often used in textbooks to demonstrate that the energy of an ideal gas is...
7. ### Calculate Final volume and temperature of piston

Homework Statement One cylinder in the diesel engine of a truck has an initial volume of 640 cm3. Air is admitted to the cylinder at 30°C and a pressure of 1.0 atm. The piston rod then does 500 J of work to rapidly compress the air. What are its final temperature and volume? Homework Equations...
8. ### Renewable Energy Concept - Stirling Engine Composting

So I've got this crazy idea. To put it simply, to use the heat from anaerobic composting to power hot-air engine, specifically a Stirling Engine. Based solely on my own reading, the center of a closed composting heap can reach anywhere from 120-160 degrees without killing the microorganisms...
9. ### Gas Laws -- why calculate the mean square speed at 273K?

Homework Statement Why is the formula ##p = \frac{1}{3}\rho<c^2>## used to calculate the mean square speed at 273K? Why 273K?
10. ### What Is the Highest Temperature Reached in the Ideal Gas Cycle?

Question (see attached diagram): PV diagram with 7.5 moles of ideal diatomic gas through cycle a, b and c. What is the highest temperature reached by the gas during the cycle? (multiple choice answers 180, 325, 208 and 100 C, i know answer is 208 C but I'm not getting it!) It is a PV diagram...
11. ### B Is this a printing error? (book example problem -- radius of a molecule)

Question :- The critical volume of a gas is 0.072 L mol-1. What will be the radius of the molecule in cm ? Answer in the book :- ##V_c = 3b \implies b = 0.024 L mol## ##\therefore## for every molecule ##b = {24 \text{cm}^3\over 6 \times 10^{23}} = 4 \times 10^{-23}\text{cm}^3## per...
12. ### 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...
13. ### Collecting gas over water with a eudiometer

Homework Statement When, using a eudiometer in a lab to collect gas over water, if you have to switch eudiometers is the final volume of water displaced equal to the water displaced in the first tube + the water displaced in the second, and would the pressure be calculated through the total...
14. ### Thermochemistry & Gases in Electrical Engineering?

I'm a first year electrical engineering student and in my General Chemistry class, every other week, we're required to write a paragraph about how each weeks material relates to your future career. As I am in electrical engineering, I don't see much relation to any topic. This week is...
15. ### Pressure Drop In Bulb : Application of Graham's Law

Homework Statement The pressure in a bulb dropped from 2000 to 1500 mm of mercury in 50 minutes when the contained oxygen leaked through a small hole. The bulb was then evacuated. A mixture of oxygen and another gas of molecular weight 72 in the molar ratio of 1 : 1 at a total pressure of 6000...
16. ### B Hello all, lay-man's question about gas laws

Hello all, I have perused this forum for a while now. I've never signed up because I have nothing to offer you folks. I'm not evan an amateur, I'm just interested in physics. I'm a critical care / flight medic, so my understanding of physics is really, really, really limited. Although, I'm...
17. ### How to Calculate Work Done by a Gas in Thermodynamics?

Homework Statement Please see the attached image Homework Equations pv=nRTThe Attempt at a Solution i don't know how to calculate the work done by the gas in the question and i calculated the change in internal energy.
18. ### Total Pressure of the System

Homework Statement Introduced into a 1.70 −L flask is 0.120 mol of PCl5(g); the flask is held at a temperature of 227∘C until equilibrium is established. PCl5(g)⇌PCl3(g)+Cl2(g) What is the total pressure of the gases in the flask at this point? [Hint: Use data from Appendix D in the textbook...
19. ### Gas pressures with (hypothetical) filter

Imagine I have 2 constant-volume, constant-temperature containers. Container A has a volume of 10 L and one Container B has a volume of 5 L. My hypothetical gases Ideal Gas A and Ideal Gas B have the same properties as each other (temperature, mass, energy, heat capacity, blah blah blah). If I...
20. ### Problem involving gas laws and hydrostatics

Homework Statement A glass tube filled with air at room temperature is 1.54m long. The tube is closed on one end, and open on the other. When submerging the open end in water, the water in the tube rises by 0.14m. How much of the tube is above the water's surface? The correct answer is 0.40m...
21. ### Does Increasing Molecules in a Constant Temperature Container Affect Pressure?

Homework Statement If number of molecules in a closed container increases and it is kept at a constant tempurature, what happens to the pressure? I was confused because I thought if you add molecules the temputature would go up so keeping temputature a constant would have no affect on the...
22. ### Some Thoughts on Atmospheric Systems

Atmospheric sciences are—much like the sister science of astronomy—primarily observational sciences and not primarily experimental sciences. The atmospheric systems that we study are not well-defined systems under controlled conditions, but ill-defined systems under completely uncontrolled...
23. ### Thermodynamics Problem - Adiabatic Reversible Process....

Homework Statement A specific type of ideal gas has a specific heat capacity at constant pressure (cp=cv+R) that is a function of temperature T, such that cp=0.5+876T, where cp has units of J/kg/K and T has units of K. The gas, which is initially at T1 = 294 K and P1 = 1x105 Pa, undergoes a...
24. ### Gas Laws - What is the final pressure in the system?

Homework Statement Two glass vessels M and N are connected by a closed valve. M contains helium at 20 °C at a pressure of 1 × 10^5 Pa. N has been evacuated, and has three times the volume of M. In an experiment, the valve is opened and the temperature of the whole apparatus is raised to 100...
25. ### Calculating Mass in a Gas Stoichiometry Problem

Hi all, While studying for my exam (and doing review questions) I came across a problem that I couldn't solve: 5. Zirconium metal and chlorine gas react to form zirconium (IV) chloride Zr + 2Cl2 = ZrCl4 a) What volume of chlorine gas must be used at 350 degrees Celsius and 50 kPa to produce...
26. ### What is the molecular diameter of hydrogen using Van der Waals coefficients?

Homework Statement Calculate the molecular diameter of hydrogen, assuming the spherical shape on the basis of van der Waals coefficients. Van der Waals Coefficients for hydrogen a = 0.244 atm L2.mol-2 b*103 = 26.6 L.mol-1 Homework...
27. ### Solve Combined Gas Law: National 5 Physics Exam Help

I am studying National 5 physics, and my exam is tomorrow. I need some last-minute help. I'm struggling a little bit with the combined gas law, P1V1/T1 = P2V2/T2, and I'm not sure why. It would help me a lot if you could show step-by-step how the formula is used. Thanks for your time, it's very...
28. ### Gas laws: calculating total volume

Homework Statement 5 lbs of nitroglycerin detonates. What is the total volume of the gases produced? Homework Equations PV=nRT The Attempt at a Solution I used the balance chemical equation of the decomposition of nitroglycerin and used stoichiometry to find the number of moles of nitrogen...
29. ### Thermodynamics - Work Done in a Closed System (Polytropic?)

Just want to check that I've used the correct method for this thermodynamics question I've been set. Any clarification would be greatly appreciated. So I have a closed system in which a gas is compressed from a pressure of 3 bar absolute to 5 bar absolute. The volume changes from 0.9m^3 to...
30. ### Gas Laws -- An astronaut breathing presurized air

Homework Statement An Astronaut on a spacewalk has an oxygen tank strapped to his suit. The oxygen in it is pressurised to 5 atmospheres (5x10^5 Pa), and the volume of the tank is 15 litres. a) The oxygen is pumped to his mouth at atmospheric pressure (1x10^5 Pa). What is the maximum volume of...
31. ### Thermodynamics and Gas Laws

There is a container of a fixed volume filled with gas. There is a second container with a piston filled with gas. The containers are filled with the same amount of gas, have the same pressure, have the same volume (the piston is placed so the gases of each container occupy the same volume)...
32. ### Ideal gas laws in cosmology usage

The ideal gas has the following requirements. 1) there are no intermolecular forces between the molecules. 2) the volume of the gas is negligible compared to the volume of the container they occupy. 3) the interactions between the particles and the container is perfectly elastic (total kinetic...
33. ### Are the gas laws compeletely true?

I've looked alittle at the gas laws and I get the feeling that they are simplified. From what I can see they don't take intermolecular forces into account. Will the intermolecular forces simply disappear or just get so weak that we don't take them into account? The gas law I'm thinking about...
34. ### Ideal gas laws question Help

Ideal gas laws question.. Help! Homework Statement Volume of 150cm^3 of an ideal gas has an initial temp. Of 20 degrees celcius and an initial pressure of 1 atm. What is the final pressure if the volume is reduced to 100cm^3 and the temp is raised to 40 degrees celcius. Homework...
35. ### Ideal gas laws dealing with pressure volume and temp.

Homework Statement An ideal gas has the following initial conditions: Vi = 520 cm3, Pi = 3 atm, and Ti = 100°C. What is its final temperature if the pressure is reduced to 1 atm and the volume expands to 1000 cm3? Homework Equations I used the equation p1 x v1 / t1 = p2 x v2 / t2...
36. ### Understanding the Combined Gas Law

What do textbooks mean when the gas laws are "combined" to make the ideal gas law? I think that if the equations were combined, the result would look something like this: P = k(T)T P = k(V)/V P = k(n)n P^3 = (k(T)T * k(V)*k(n)n)/V or P/T = k(T) PV = k(V) P/n =...
37. ### What is the Maximum Pressure in kPa for Ammonia in the Haber Process?

Hello everyone, I'm doing some practice problems for my final exam. I came across this question: «The Haber process is being used at a pressure of 76 000 mmHg at a temperature of 450°C. Gaseous ammonia is cooled and collected after its production, in order that its temperature does not...
38. ### Understanding Gas Laws: Explaining the Relationship Between Pressure and Volume

Hey guys. I'm new to the forum :). I'm a high school student who takes physical sciences as one of my subject. The thing is that I've been confused about something I read on chemistry. This might sound stupid but please try and understand that this is confusing me. In the gas laws, Gay Lussac's...
39. ### Help with rearranging equations for gas laws

Homework Statement An equation of state that has been used to model the behaviour of a fixed amount of a real gas is (p + a/v2) (V - b) = ZT In the equation, Z, a and b are constants, and P represents pressure, V represents volume, and T represents temperature. The constant Z depends on the...
40. ### Solve Gas Laws Confusion - P, V, T & n

Hey guys ! I am confused when textbooks say that P (pressure), V (volume), T (temperature), n (moles) or any combinations of these be CONSTANTS. Especially when it comes down to the three gas laws. I don't understand what some variable being a constant means :( and hence the immense confusion...
41. ### Application of gas laws to home mold problems

I'm a mold inspector looking for an answer to gases from mold growing in wall cavities of a house. The issue is whether gases penetrate into room air (which I can test for) and what the best approach (short of gutting the house) is to reduce exposure to mold gases in the house. The two...
42. ### Finding Gas Mass Using Heat Exchange at Constant Pressure and Volume

Homework Statement The temperature of an ideal gas (M=28kg/mole) has increased 14K by adding 29J of heat at a constant pressure. To cool the gas back to the initaial temperature 20.7J of heat is extracted from the gas at a constant volume. Find the mass of the gas. Homework Equations...
43. ### Solve Gas Law: Volume at STP from Pressure & Temp of Hydrogen Gas

Homework Statement Hydrogen gas is collected over water at 25°C. The atmospheric pressure in the room is 745 mm Hg and the volume of gas in the container is 43.5mL. The vapor pressure of water at 25°C is 23.8 mm Hg. Determine the volume the gas would occupy at STP. Homework Equations...
44. ### Pressure and Temperature question: Ideal Gas Laws

Homework Statement Find the pressure and temperature when given the following data on helium gas: Volume (V) = 0.10 m^3 ** Helium mass (m) = 4.0 amu ** Number of atoms (N) = 3.0 x 10^24 Assuming PV = 1 then P=1/V then Pressure = 1.0 / 0.10m^3 = 10Pa Homework Equations PV = NkT...
45. ### Solve Chemistry Gas Laws Homework: V1/T1 = v2/T2

Homework Statement People who are angry sometimes say that the feel as if they will explode. If a calm person with a lung capacity of 3.5L and a body temp of 36C gets angry, what will the volume of the persons lungs be if their temp rises to 39C. Homework Equations V1/T1 = v2/T2...
46. ### Find the ratio (ideal gas laws) how to get a Ratio between two numberS>

Homework Statement The temperature of a fixed mass of gas drops from 127 C to 27 oC under constant pressure. Find the ratio of the new volume to the original volume. C. 3:4 D. 4:3 E. 1:1 A and B arent here because i have gotten them wrong. Homework Equations Ideal gas law: PV=...
47. ### Solving Gas Laws: 3H2 + N2 -> 2NH3 at 110 ATM

It's a gas problem: 3 volumes N2 and 1 volume of H2 react at 344 degrees Celsius to form NH3. The equilibrium total pressure is 110 ATM and is 41.49% NH3 by volume. Find Kp assuming the gases behave ideally. So I started by assuming that I had 100L of gas. I worked the ICE table like so...
48. ### Gas Laws Weakness: Moving Plunger In Heats Gas, But Moving Out May Not Cool It

Did that get your attention? Ok, so I'm mosty kidding, but I have a conundrum for you that exposes one of the weaknesses of the gas laws. Ready? In my astronomy class last quarter, we had to do a brief overview of physics, because physics isn't a pre-req, and some people had never taken...
49. ### Gas Laws Homework: Calculate Mass of Propane Used

Homework Statement 8. A cylinder 1.00 m tall with an inside diameter of 0.120 m is used to hold propane gas (molar mass: 44.1 g.mol-1) for use in a barbeque. It is initially filled with a gas until the gauge pressure is 1.30 x 107 Pa and the temperature is 22.0⁰C. The temperature of the gas...
50. ### Electrical engineering applications requiring the use of gas laws such as PV=NRT etc

Have you ever used the Ideal Gas Law, Charles' Law, Boyls' Law, or the Combined Gas Law for anything in electrical engineering?