Physical and chemical laws describing the properties and behavior of gases.

learn more… | top users | synonyms

1
vote
1answer
24 views

Why does a container in which a match burning cause suction?

As you see in picture a burning match in a container causes suction and this is a Traditional Therapeutic method to relive bone pain. What is the reason? I think it should be related to gas ...
2
votes
1answer
21 views

What determines humidity limit / dew point of the air? - Why can air only hold a certain amount of water?

From Wikipedia: The dew point is the temperature at which the water vapor in a sample of air at constant barometric pressure condenses into liquid water at the same rate at which it evaporates. At ...
1
vote
1answer
28 views

Collection of gas over water

When you collect a gas over water, you have to account for the mixed in water vapor by subtracting the room pressure from water vapor pressure. However, why do you not do something similar for volume, ...
2
votes
1answer
44 views

Prepare 1 liter of 28% NH3(aq) solution from 1 gal of %10 NH3(aq)

I have one gallon of commercial, surfactant free, ammonium hydroxide solution that I would like to use to prepare a concentrated solution. I have two options as I see it, and I am still getting into ...
1
vote
3answers
83 views

In order to be a gas does the pressure exerted by the gas has to be more than the atmospheric pressure?

In order to be a gas does the pressure exerted by the gas has to be more than the atmospheric pressure? Really simple, I think yes to this question but teacher says no. So what is your view into this? ...
0
votes
1answer
14 views

Is there any graph that depicts the deviation of real gases from Charle's law?

I am looking for a graph that shows the basic deviation of a gas from the Charle's law. The graph should be for different values of constant pressures.This would help me evaluate how gases follow ...
0
votes
0answers
23 views

Reducing NOx with Ammonia. Practical in a gasifier?

Sorry if this is an outright stupid question. I am no chemist... For Nitric Oxide: $2{NH_{3}} + 2 NO => 2 {N_{2}} + {H_{2}} + 2{H_{2}O}$ For Nitrogen Dioxide: $2{NH_{3}} + 2{NO_{2}} => ...
0
votes
2answers
32 views

Why two ( or more) gases have proportional volumes at constant pressure and temp.? (Avogadro's Law)

I am in real confusion over Avogadro's Law.. In some of the problems I did on gas laws, there are the number of moles of the gas, the temperature. and the pressure. And it expects me to find the ...
1
vote
1answer
25 views

Is this the correct equation for the mean free path?

$\lambda=\frac{KT}{\sigma p}$ is the equation given in my textbook but everywhere else I look it is different. Is it wrong? The derivation is as follows: $$\lambda = \frac{v_{rel}}{z}$$ where ...
1
vote
1answer
32 views

How do derive the equation for relative velocity of gas molecules

The relative velocity is $$v_{rel}=\sqrt2v_{mean}$$ where $v_{mean}=(\frac{8KT}{\pi m})^{\frac12}$$$v_{rel}=(\frac{16KT}{\pi \frac m2})^{\frac12}$$ because the reduced mass of two of the same ...
1
vote
2answers
61 views

How to get the first step of the derivation of the Maxwell-Boltzmann distribution

To derive the Maxwell-Boltzmann distribution the first step requires the knowledge that the equation will take the form $$f(v)=Ke^{-\epsilon/ kT}$$ where $\epsilon$ is the sum of the kinetic energies ...
2
votes
1answer
35 views

Calculate the root-mean-squared speed of free electrons in the Sun's corona given pressure, temperature and mass of an electron

$m_e=9.1×^{-31}kg$, $T=2×10^{6}K$ and $p=0.030Pa$ the solution is given as: $5.4×10^6 ms^{-1}$ but I got $9.5×10^6 ms^{-1}$ using the following method (which does not use the value given for pressure. ...
-1
votes
1answer
68 views

Calculate the frequency so that the wavelength of sound in air would be equal to the mean free path in oxygen at 1.0 atm and 0ºC

Take the diameter of the oxygen molecule to be $3.0×10^{-10}$ m. Here's what I did: $$\lambda_{mfp}=\frac {K_BT}{\sigma p}$$ $p$ is pressure. Mfp stands for mean free path. ...
2
votes
1answer
43 views

Why can a gas only transmit sound waves whose wavelength is long compared with the mean free path?

Also when can this fact be useful? I don't really understand at all why this might be the case so any help would be appreciated.
5
votes
1answer
63 views

Percent composition, maybe?

I've attempted to solve this problem with percent composition, but it says the answer is wrong. Is it a PV=nRT problem, and if so, can I use the units as they are given? A 0.02867 g sample of gas ...
0
votes
1answer
16 views

A 4.00 L sample of gas is cooled from 67 °C to a temperature at which its volume is 2.60 L [closed]

A $4~\mathrm{L}$ sample of gas is cooled from $67~\mathrm{°C}$ to a temperature at which its volume is $2.6~\mathrm{L}$. What is this new temperature? Assume no change in pressure of the gas.
0
votes
1answer
10 views

Quick Stoich & Gasses

I have a quick question in Stoich and Gasses, I however could not get any far, any answer will be appreciated. Thank You. A sample of $\ce{Pb(NO3)2}$ is heated, yielding $\ce{O2, NO2\ gas,\ and\ ...
0
votes
1answer
43 views

Gas Stoichiometry & Ideal Gas Law

I need a little help with one of the problems below. Any help on the problem below will be appreciated. I don't want to sound like an idiot, I will also provide my work. Solid $\ce{NaHCO3}$ ...
1
vote
1answer
21 views

What will happen to the entropy and free energy of the gasses when the partition is removed?

Consider a container of volume $ 5.0$ L that is divided into two compartments of equal size. In the left compartment there is nitrogen at $1.0$ $atm$ and $25 °C$; in the right ...
1
vote
1answer
43 views

What conditions can cause a material to exist as a gas?

So my question is, how can something exist a gas. Is it when the pressure exerted by the gas is greater than the atmospheric pressure, then it is a gas? And also how do manometers work, how can you ...
2
votes
1answer
55 views

Where does this equation for the activity in the gas phase equilibrium between N2, H2 and NH3 come from?

I have a question with Equilibrium Constant. I understand that for a reaction in equilibrium $aA +bB \rightleftharpoons cC +dD$ $$K_c= \frac{[C]^c[D]^d}{[A]^a[B]^b}$$ and $K_p$ is just using the ...
2
votes
1answer
68 views

Ideal gas law derivation from kinetic theory

Consider the derivation of the ideal gas law from kinetic theory presented here: http://en.wikipedia.org/wiki/Kinetic_theory I have some questions This derivation assumes the container is a cube, ...
3
votes
1answer
31 views

Proportion of gases in Ideal Gas Mixture?

Suppose methane ($CH_4$) and ethane ($C_2H_6$) in a container. The specific gravity is $r_g=0.6$. I think this means $0.6=\frac{\rho_{CH_4}}{\rho_{C_2H_6}}$. Now I am trying to understand the ...
3
votes
2answers
44 views

Compressible Factor

I 've a soft question on the terminology of compressibility factor. It is termed compressible factor because, its value determines how any reals gas is compressible with respect to an ideal gas ...
1
vote
3answers
44 views

Plotting p/T against T

This is about the ideal gas equation $$pV=nRT$$ to plot ${p}\over{T}$ against $T$, where ${nR}\over{V}$ is constant. How would this graph look like?
0
votes
0answers
39 views

How to determine an unknown gas in a tube with a massless piston at equilibrium conditions?

There is a massless piston that can move freely in a horizontal tube that is closed at both ends. To the left, there is a sample of helium gas at $300~\mathrm{K}$ and $4~\mathrm{atm}$. To the ...
2
votes
0answers
52 views

How to find Gibbs energy for a real gas

I'm asked to find $\Delta G$ for the isothermal compression of $N_{2(g)}$ (real gas) at $0°C$ if the gas expands from $P=1\space atm$ to $P=1000 \space atm$. The fugacity coefficients are ...
1
vote
4answers
98 views

How to find the empirical formula for an nitrogen oxygen compound from the given mass of nitrogen and the product?

$5.00~\mathrm{g}$ of nitrogen is completely converted into an oxide of nitrogen. The mass of the oxide formed is $19.3~\mathrm{g}$. The empirical formula of the oxide would be? My working: ...
2
votes
1answer
58 views

Gas laws question, condensed partial pressure?

So I'm relatively new to gas laws as I just started learning it at school. I've been doing fine so far until I got stuck on this question, any ideas? A mixture of three gases N2, CO2 and O2 has a ...
4
votes
1answer
72 views

Volume of different gas in a container

I know that technically two or more gases in one container should have different volumes. But when you imagine the gas molecules being mixed together, it look sorta like the two gases have the exact ...
1
vote
1answer
750 views

Using combined gas law to calculate the volume of dry hydrogen gas

Pv/t = pv/t is the equation of combined gas law. Say if the volume of wet hydrogen gas is 40.48ml does this equation still work if part of that volume is water vapor. Or in another word, does the ...
1
vote
0answers
17 views

How to calculate the volume of dry hydrogen in magnesium/ HCl reaction [duplicate]

Sorry if this will sound trivial, I am not too sure if the moles of $H_2$ in the equation $Mg(s) + 2HCl(aq)\rightarrow MgCl_2(aq) + H_2$ is that of dry or wet hydrogen. If the $H_2$ refers to wet ...
0
votes
1answer
29 views

Stoichiometry of Gaseous Reactions

The Question: How many liters of $H_2S$ would be required to react with excess oxygen to produce $12.0$ $L$ of $SO_2$? The reaction yield is $88.5$%. Assume constant temperature and pressure ...
0
votes
1answer
69 views

How does pressure change reflects in this formula? [closed]

The pressure is missing or I guess is integrated in the adiabatic constant. But I don't know how to even derive the adiabatic constant for a certain gas.
1
vote
1answer
99 views

Finding Root-Mean-Square of Ne using kinetic energy?

I am not being able to solve the following question: -Find the root-mean-square speed of $\ce{Ne}$ atoms at the temperature at which their kinetic energy is $\mathrm{6.24\ kJ/mol}$. I tried ...
0
votes
1answer
60 views

Proof of kinetic energy equation

Is there a way to prove that $\frac{1}{2} mv^2 $$= \frac{3}{2}RT$ The first one is kinetic energy and the second is the average kinetic energy. Can this be proved by component of velocity.
0
votes
0answers
35 views

A way to rationalize avogadro's hypothesis

How can one rationalize avogadro's hypothesis using the equation of kinetic molecular theory. Did you see anything? I can't
0
votes
1answer
81 views

Will the propane liquefy?

Consider a 1:1 mix of propane and nitrogen at 60 °F and 75 psi. Will the propane liquefy if pressure is increased to 200 psi? This is a real world question. I am experimenting in the oilfield with a ...
0
votes
1answer
77 views

Undergrad Kinetic Molecular Theory

Gas A and B are placed together in a sealed container at room temperature and are pressurized to 2.5atm. After a period of time, there is a border between the two gases. Given A has a density ...
3
votes
1answer
56 views

Significance of Kinetic Velocities?

In the concept of Kinetic Molecular Theory we have rms(root mean square), avg(average) and mp(most probable) velocities. I understand the concept well. But my question is why do we have three ...
3
votes
1answer
66 views

Which gas is easier to compress, the ideal gas or a real gas?

Since the pressure of a real gas is less than that of the ideal gas and its volume is more than that of ideal gas, I am assuming that the real gas is difficult to compress in comparison to an ideal ...
0
votes
1answer
113 views

Calculating collision diameter with viscosity, but not having the mass given

I've got a homework question i'm stumped on. The viscosity of the ethylene gas was measured at $99.8*10^{-7} \textrm{ N s m}^{-2}$ at $288 \textrm {K}$. Calculate the collision diameter in ...
2
votes
1answer
44 views

The Van Der Waals Equation - High T and High $V_m$

This one is for my physical chemistry homework and I'm having trouble finding the answer. At high temperatures the Van Der Waals equation has the form $$P\approx\frac{RT}{V_M-b}$$ What would ...
1
vote
1answer
32 views

Addition of combined gas law constant

There are two containers connected to each other but separated by a cork. If container(1) has a gas $G_1$ at a volume $V_1$, pressure $P_1$ and temperature $T_1$ and similarly in container(2) there ...
1
vote
1answer
17 views

How to determine the pressure to output a gas to achieve a particular gas flow rate?

I have a 420-liter (14.9 cubic ft) helium cylinder and a pressure regulator with a gauge supporting up to 160 psi. My requirement is to ensure a flow of 10 to 15 liters / min. How do I determine the ...
0
votes
2answers
62 views

The relationships between n , T , P , V for a gas?

The symbols : T : temperature // V : volume // P : pressure // n : number of mole what it is clearly known about the relationship between one another is : P is inversely proportional to V ( from ...
2
votes
3answers
123 views

What is the partial pressure of oxygen in this mixture of oxygen and argon?

A $19.3\:\mathrm{g}$ mixture of oxygen and argon is found to occupy a volume of $16.2\:\mathrm{L}$ when measured at $675.9\:\mathrm{mmHg}$ and $43.4\:\mathrm{^\circ{}C}$. What is the partial ...
2
votes
1answer
16 views

A 1.00 L gas at 100. °C and 500. torr contains 70.0 % He and 30.0 % Ne by mass. What is the partial pressure of He?

A $1.00~\mathrm{L}$ gas at $100~^\circ\mathrm{C}$ and $500~\mathrm{torr}$ contains $70.0\%~\ce{He}$ and $30.0\%~\ce{Ne}$ by mass. What is the partial pressure of $\ce{He}$? My answer is ...
2
votes
1answer
47 views

What is the relationship between pressure and stoichiometry ratios

This is the question from the textbook. Ozone O3 can be prepared in the laboratory by passing an electrical discharge through oxygen gas. Assume that an evacuated steel vessel with a volume of 10L ...
1
vote
3answers
46 views

What are the units for m in the average kinetic energy formula?

For the equation $E_k=\frac{1}{2}mu^2$ what does the $m$ variable represent? I would say mass but the textbook does not say explicitly that it is anything.