Skip to main content

Questions tagged [gas-laws]

Physical and chemical laws describing the properties and behavior of gases. This tag currently applies to properties and laws concerning both ideal and real gases.

Filter by
Sorted by
Tagged with
77 votes
6 answers
26k views

Why would breathing pure oxygen be a bad idea?

My textbook mentions that SCUBA tanks often contain a mixture of oxygen and nitrogen along with a little helium which serves as a diluent. Now as I remember it, divers take care not to surface too ...
paracetamol's user avatar
  • 18.7k
48 votes
2 answers
18k views

What volume does one mole of an ideal gas occupy?

This has been bugging me for a while now... Obviously, to calculate the volume/space occupied by a mole of (an ideal) gas, you'll have to specify temperature ($T$) and pressure ($P$), find the gas ...
paracetamol's user avatar
  • 18.7k
44 votes
1 answer
6k views

Why can we still breathe in valleys? [duplicate]

Air is 1% argon. Argon is heavier than air. Why doesn't the argon concentrate in low-lying areas, choking out life there?
Stack Tracer's user avatar
25 votes
6 answers
1k views

Why are equations of state for a non-ideal gas so elusive?

The ideal gas equation (daresay "law") is a fascinating combination of the work of dozens of scientists over a long period of time. I encountered Van der Waals interpretation for non-ideal gases ...
jonsca's user avatar
  • 3,007
21 votes
2 answers
5k views

What is a rigorous definition of gas volume, and how is the Van der Waals equation derived?

I am confused about the justification for the corrections to the ideal gas law in the Van der Waals equation: $$p=\frac{nRT}{V-nb}-a\left(\frac{n}{V}\right)^2$$ I understand that the equation ...
Sean Mackesey's user avatar
20 votes
2 answers
21k views

Why is the van der Waals coefficient b equal to four times the volume of the particle?

In the van der Waals equation of state $$\left[p + a\left(\frac{n}{V}\right)^2\right](V-nb) = nRT$$ the coefficient $b$ is supposed to represent the volume occupied by the particles. Why then is it ...
piyush pachauri's user avatar
17 votes
4 answers
5k views

How could the ideal gas law be discovered from experiments on real gases?

The gas laws, namely Boyle's Law, Charles' Law, Avogadro's Law and Gay-Lussac's Law, are all experimental laws. Combining these laws, we get the ideal gas law $pV=nRT$. Also, "real life" gases do not ...
user avatar
16 votes
4 answers
11k views

Why don't heavy and light gases separate in the atmosphere?

Everyone must have heard that balloons are filled with helium, and the fact associated with it that helium gas is light and light gases always go upward. There comes a question to mind: if the molar ...
Vidyanshu Mishra's user avatar
16 votes
2 answers
63k views

When I heat up a balloon, does the air inside increase in pressure as well as volume?

When I heat up a balloon, does the air inside the balloon increase in pressure as well as volume? I thought pressure and volume were inversely proportional? Or does pressure and volume increase as ...
John's user avatar
  • 171
16 votes
7 answers
25k views

What's the difference between perfect and ideal gas?

There are all kinds of different dinstinctions in the internet, and I'd like to see what you guys thought. Actually, I've been asked if the heat capacity of an ideal gas es independent of temperature....
DLV's user avatar
  • 813
15 votes
3 answers
10k views

Why do helium balloons expand in volume as they go higher?

I realize as balloons go higher, the atmospheric pressure decreases, doing less to counteract the force of the gas particles pushing against the inner walls of the balloon. But at the same time, doesn'...
Nick's user avatar
  • 343
15 votes
1 answer
3k views

Why is the carbon dioxide we exhale transparent?

Why is carbon dioxide that comes from dry ice opaque and smoky while the carbon dioxide that we exhale transparent?
Krikor Ailanjian's user avatar
15 votes
3 answers
4k views

PV=nRT approximation on other planets?

In Chemistry class yesterday, I learned that real gases with low atomic masses behave like an ideal gas at high temperatures and low pressure. Since on earth at sea level the pressure is close to $1\ \...
James Smith's user avatar
15 votes
1 answer
582 views

How does composition of air affect vapor saturation limit?

Suppose we hold temperature, pressure, and gas composition (say, a standard atmosphere) constant. Then we know that if we allow the water content of the air to vary it can range between 0 and some ...
feetwet's user avatar
  • 3,340
14 votes
2 answers
34k views

Reason for negative Joule Thomson coefficient of Helium and Hydrogen at NTP conditions

Recently, while reading my textbook I came to know that Helium, Hydrogen and Neon are the only gases which have negative Joule Thomson coefficient at NTP conditions, i.e heating effect is observed ...
SirXYZ's user avatar
  • 365
13 votes
3 answers
148k views

What is the carbon dioxide content of a soda can or bottle?

I sort of know how carbonated beverages are carbonated: a lot of $\ce{CO2}$ gets pushed into the liquid, and the container is sealed. There are at least two things I don't know. First, how much carbon ...
Colin McFaul's user avatar
  • 1,821
13 votes
2 answers
3k views

What causes spray cans to get cooler when shaken?

I've been searching the web for this phenomenon and surprisingly I found only one post about it. And the reply to this question about canned air begins with words: I don't know about the shaking ...
Tomáš Zato's user avatar
  • 2,498
13 votes
2 answers
4k views

Why do some gases have lower value of Z for a particular pressure?

In the above graph,the minima of the curve for methane is more than that of nitrogen. Also, for a given value of pressure, the value of $Z$ for methane is less than that of nitrogen. They seem to meet ...
Aditya Dev's user avatar
  • 7,826
12 votes
4 answers
2k views

Why does gas not liquify at a temperature above the critical temperature no matter how much pressure is applied on it? Why? [duplicate]

My textbook says that critical temperature is the temperature above which a gas cannot be liquified no matter how much pressure we apply on it. But why? What is so special about this 'critical ...
user281837's user avatar
12 votes
3 answers
25k views

Why is the pressure correction in the van der Waals equation proportional to (n/V)^2?

The van der Waals equation for real gases is stated as follows: $$\left(P + \frac{an^2}{V^2}\right)(V - nb) = nRT$$ For the coefficient $b$, we can reason out that more the number of molecules, the ...
Yashas's user avatar
  • 2,106
12 votes
2 answers
4k views

Can the van der Waals coefficients be negative in the van der Waals equation for real gases?

A gas described by van der Waals equation has the pressure that is lower than the pressure exerted by the same gas behaving ideally. True or false? My approach $$P(\text{ideal}) = P(\text{real}) + P(...
Groverkss's user avatar
  • 367
12 votes
2 answers
452 views

Vapor Pressure Paradox

This is quite an interesting situation I had thought of. Consider two beakers, each containing $\pu{180 g}$ of water. Also, suppose one of the two has $\pu{1.8 g}$ of glucose dissolved in it. Let's ...
Pritt says Reinstate Monica's user avatar
11 votes
3 answers
32k views

Relation between constant-pressure and constant-volume heat capacities: Cp - Cv = nR

For an ideal gas, we have $$C_p - C_V = nR$$ where $C_p$ is heat capacity at constant pressure, $C_V$ is heat capacity at constant volume, $n$ is amount of substance, and $R=N_\mathrm A\cdot k_\...
orthocresol's user avatar
  • 71.5k
11 votes
3 answers
10k views

How does the "kreosan" Coca-Cola rocket work?

A YouTube channel called "kreosan" (made by Russian-speaking people who I believe live in Ukraine) posted a video showing rockets made from bottles of Coca-Cola. Here's what I've figured out from the ...
steveha's user avatar
  • 119
10 votes
3 answers
254 views

Perplexing claim in Chang and Overby's "General Chemistry"

I'm reading the chapter on gases in Chang and Overby's book "General Chemistry: The Essential Concepts" [1, p. 145], and the following passage is causing me some confusion: The work of the ...
Jesse's user avatar
  • 101
10 votes
5 answers
4k views

Pressure vs volume plot for real gas and ideal gas

Background Recently I have been studying about the states of matter and came to the topic of ideal gases and real gases, and the laws related to them. While studying it from my textbook, I saw the ...
user avatar
10 votes
2 answers
73k views

Isothermal vs. adiabatic compression of gas in terms of required energy

I am working on an instruction manual of sorts to be used with an introductory course in thermodynamics. As an example of problem solving, I attempt to answer the following question: If you have ...
oveoyas's user avatar
  • 772
9 votes
1 answer
4k views

Why is dp/dv zero for a real gas in critical conditions?

I have read this fact in various websites but cannot understand the reason. What is an intuitive explanation of this?
Hema's user avatar
  • 677
9 votes
3 answers
2k views

Comparing van der Waals constant for gases

How can I compare the van der Waals constant $a$ (the liquefication constant) for different compounds based on my knowledge of bonding in the compound? Let's pick the following sample set: $$ \...
Swadhin's user avatar
  • 307
9 votes
1 answer
1k views

Variation of compressiblity factor with temperature

While I certainly understand the order of temperatures, I can't find a reason for the curves to intersect at one common point. Why do the curves intersect at one point? or do they really intersect at ...
Yashas's user avatar
  • 2,106
8 votes
2 answers
11k views

Do 1 mole of both dioxygen gas and its atoms occupy 22.4 litres at STP?

The ideal gas law states: One mole of an ideal gas will occupy a volume of $\pu{22.4 liters}$ at STP. Does this mean that both $\pu{1 mole}$ of $\ce{O}$ would occupy $\pu{22.4 L}$ (or if this ...
K-Feldspar's user avatar
  • 2,853
8 votes
1 answer
740 views

Confusion in Van der Waals Equation

I understand that the behavior of ideal gases deviates largely from that of real gases in terms of pressure exerted by the gas molecules on the container in which it is present, space available for ...
anotherhyooman's user avatar
8 votes
2 answers
1k views

Ideal Gas Equation Contradiction [duplicate]

You have a regular balloon, and you decide to heat it up. The gas particles inside the balloon will gain kinetic energy, and so, the gaseous particles will collide with the internal wall of the ...
StopReadingThisUsername's user avatar
8 votes
1 answer
11k views

In Graham's law, is the rate of effusion only dependent on molar mass?

According to Graham's Law, the effusion rate of a gas is inversely proportional to the square root of the molar mass of the gas. However, consider this situation: We have s balloon with 1 mole of ...
user11629's user avatar
  • 972
8 votes
2 answers
436 views

How did Joseph-Louis Proust know what gases weighed?

Proust's work led him to conclude that compounds always contain the same ratio, by weight, of their constituent elements. How did he know (or deduce?) what gases weighed? Precise answers appreciated ...
Ali's user avatar
  • 91
8 votes
1 answer
234 views

If something is not hydrophilic, is it necessarily hydrophobic?

Is it possible to create hydrophobic water? Two species are phobic within some medium under some conditions when they don't here together (cohere if they're the same species; adhere otherwise). To be ...
techno.stan's user avatar
8 votes
1 answer
1k 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 ...
zordman's user avatar
  • 373
8 votes
1 answer
3k views

Is this equation of state original?

I created this equation of state as a personal undergraduate summer project (here is the link) seven years ago: $$\frac{PV}{nRT}-1 \propto \left(\frac{nRT}{PV}\right)^2 \left[\left(\frac{nRT}{PV}\...
KingChem's user avatar
  • 109
8 votes
2 answers
2k views

Will CO2 bubbles ever fully dissolve in water?

Background: Many aquarists keep freshwater planted tanks add $\ce{CO2}$ from a pressurized canister to their aquaria to promote plant growth. The injection is at a slow rate to get dissolved $\ce{CO2}$...
Phil Frost's user avatar
8 votes
1 answer
660 views

Anomaly in van der Waals constants of noble gases

In van der Waals equation for a real gas, the equation is $$\left(P + a\frac{n^2}{V^2}\right)(V - nb) = nRT$$ where $P$ is the pressure of the real gas, $n$ is the number of moles of the gas, $R$ is ...
Cyclopropane's user avatar
  • 2,079
8 votes
1 answer
2k views

van der Waals coefficients for helium and neon

The values of the coefficient $b$ for helium and neon are $$\begin{array}{cc} \hline \text{Element} & b\text{ / }\mathrm{dm^3\ mol^{-1}} \\ \hline \ce{He} & 2.38 \times 10^{-2} \\ \ce{Ne} &...
Math The Novice 's user avatar
7 votes
3 answers
3k views

Best ways to compress and store tons of CO2? [closed]

We are looking at doing planet changing work, and removing CO2 from the atmosphere. The issue is storing the CO2. Please let us know the best ways to compress millions of tons of CO2, as we have ...
Jim Moore's user avatar
7 votes
1 answer
435 views

Dewpoint of water in relation to composition of atmosphere

A couple of colleagues and I were talking about the nature of dewpoints, specifically the dewpoint of water in relation to the chemical composition of the atmosphere in a closed space. If I remember ...
Oak Staff's user avatar
  • 311
7 votes
2 answers
2k views

Thermodynamic Derivation of Ideal Gas Law

The ideal gas law is perhaps the best-known equation of state, and admits both a derivation via the kinetic theory of gases and via statistical mechanics. But these are both microscopic theories, and ...
a-cyclohexane-molecule's user avatar
7 votes
1 answer
1k views

Determine the molecular formula of the compound using percentage composition

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 $\pu{0.02867 g}$ sample ...
Eric Lee's user avatar
7 votes
3 answers
3k views

High pressure modification to the van der Waals equation

I get that a gas behaves non-ideally under high pressure and low temperature conditions. At high pressures, the density of a gas increases and attraction forces operate among molecules due to short ...
Abmon98's user avatar
  • 517
7 votes
1 answer
5k views

Why do different gases have the same molar volume?

Molar volume: The molar volume, symbol $V_\mathrm m$ is the volume occupied by one mole of a substance (chemical element or chemical compound) at a given temperature and pressure. At S.T.P ...
Any3nymous user's user avatar
7 votes
2 answers
39k views

Calculating Compressibility factor from the Van der Waals' Gas equation

So this problem has been bugging me for a long time. According to Wikipedia the compressibility factor $Z$ is defined as the ratio of the volume occupied by a real gas divided by the volume occupied ...
Serotonin's user avatar
  • 853
7 votes
1 answer
9k views

How to calculate the pressure of an ideal gas that undergoes isothermal expansion?

A 2.35 mole sample of an ideal gas, for which $C_{\mathrm{m},v}=3R/2$ initially at $\pu{27 ^\circ C}$ and $\pu{1750 kPa}$, undergoes a two stage transformation. For each of the stages described in the ...
wei jit's user avatar
  • 291
7 votes
1 answer
770 views

Dubowski’s Formula vs Henry's law applied to alcohol sensor 'calibration'

I'm working with some hobby-level gas sensors and I've run across a "calibration" system I don't understand. A general description of this kind of gas sensor is described a bit more in this ...
uhoh's user avatar
  • 5,888

1
2 3 4 5
15