Questions tagged [pressure]
For questions about gas pressure, or the effect of pressure in general on chemical species, substances, or reactions.
309 questions
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Density and partial pressure [closed]
A sample of $\ce{NOBr}$ gas was placed in a rigid flask where it decomposes at $\pu{25 ^\circ C}$ according to the following reaction:
$$\ce{2NOBr(g) <=> 2NO(g) + Br2(g)}$$
At equilibrium, the ...
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Does the vapor pressure of a substance depend on the presence of other gases?
The Clausius-Clapeyron equation (CC equation) can be used to find the (saturated) vapor pressure of a substance ie. the gas pressure at which the two phases (vapor + liquid or vapor + solid) reach ...
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What's the equilibrium pressure of CO2 gas over sodium hydroxide?
Many (too many) decades ago in physical chemistry lessons, I seem to recall that given the enthalpy changes of reactions, and maybe phase diagrams, one could work out what equilibrium a reaction would ...
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Variation of vapour pressure with application of external pressure
Many times study of fact that with pressure of a substance only depends on the temperature and nature of the substance recently I study about dew point and bubble point.
Then I came up with this ...
user112102
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Why does van der Waals' equation of state give only one P, V pair for a particular temperature here?
I came across this question which I initially ignored believing that the data was insufficient:
Calculate the pressure exerted by one mole of $\ce{CO2}$ gas at $\pu{273 K}$ if the van der Waals' ...
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Molecular orbitals energy under pressure
Suppose we have a hydrogen molecule $\ce{H2}.$ At room temperature the average distance of the nuclei is $r_0$ (without applying pressure).
If we put $n$ hydrogen molecules in a box with volume $V_\...
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Why does CO2 diffuse out of a cylinder in the absence of a pressure difference?
Suppose I have a thermally insulated cylinder containing carbon dioxide (assuming it is ideal) at 1 atm pressure(atmospheric pressure is 1 atm). Now let's consider two cases:
CASE-1: I cut open the ...
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How to calculate Kp without knowing the volume? [closed]
I have the following chemical equation:
$$\ce{Sb2S3 + 3H2 <=> 2 Sb + 3H2S}$$
I have $\pu{1000 grams}$ of $\ce{Sb2S3}$ that reacts with $\pu{10 grams}$ of $\ce{H2}$ in a reactor at $\pu{713 K}$.
...
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Does pressure affect pH? [closed]
Since pH is the function of $\ce{H+}$ ion concentration, the change in volume will change the equilibrium according to Le Chatelier's principle and affect the pH. Is it correct, or are there any ...
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Heat released at constant pressure and temperature and heat released at constant density and temperature
Is there a relation between heat released at constant pressure and temperature and heat released at constant density and temperature?
I was reading some books on propulsion and combustion, and the ...
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Effect of addition of inert gas on concentration in an equilibrium [duplicate]
We have the following equilibrium established in a container with movable piston at atmospheric pressure.
$$\ce{N_2 (g) + 3 H2 (g) ⇌ 2NH_3 (g)}$$
Now how does the concentration of the reacting species ...
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Vapor Pressure of reaction mass undergoing an exothermic reaction
A vessel containing a reaction mass under going an exothermic reaction is under vacuum, with temperature and pressure constant. When the source of vacuum is closed, the reactor begins to increase ...
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When does a piston stop in an irreversible process?
Suppose we have an ideal gas filled inside a container fitted with a piston. The external pressure is equal to internal pressure.
If we suddenly decrease the external pressure, we say that the gas ...
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Pressure of two flasks connected to each other at different temperatures [closed]
Two flasks of equal volume connected by a narrow tube (of negligible volume) are at $\pu{27 °C}$ and contain $\pu{0.7 mol}$ of $\ce{H2}$ at $\pu{0.5 atm}$. If one of the flasks is then immersed into a ...
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Relative humidity and vapor-pressure in equilibrium
I have quite an unclear understanding of relative humidity. I am writing my understanding on the topic and please correct me wherever I'm wrong:
What I understood:
Let's say $\ce{H2O}$ has a (...
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Osmotic Pressure of Aqueous Solution
The osmotic pressure of an aqueous solution at $25$ Celsius is $92.0$ $kPa$. Calculate the boiling point
of the solution. (Assume that the density of the solution is $1.0$ $g/mL$, ignore the mass of ...
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Dissolution of CO2 in water
The following question has troubled me for a while.
For gases that are slightly soluble in water, there is a proportional relationship between the partial
pressure, $P$, and the mole fraction, $x$, ...
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Liquifying a gas above critical temperature [duplicate]
Is there any theoretical/hypothetical way through which a gas can be liquified above critical temperature? For example applying inifinjte amount of pressure to the system?
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Doesn't adding an inert gas at constant volume increase the partial pressures?
When you add an inert gas to a container of constant volume full of gases, you are basically shoving the inert gas into the container and increasing the pressure inside the container, so the partial ...
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What pressure does liquid nitrous oxide need at −45 °C?
What pressure does liquid nitrous oxide need at −45 °C to remain liquid? How can I calculate its pressure required for other temperatures?
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Is it possible to store moist air at high pressure?
Is there any way to store moist air inside a high pressure tank?
Let's suppose that I have humid air (30%) at room temperature and I want to store it at 300Bar in a tank. when I extract the fluid from ...
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Reaction stoichiometry for calculation of Kp
NH$_2$CO$_2$NH$_4$(s)⇌$2$ NH$_3$(g)+ CO$_2$(g)
I want to calculate K$_p$ for the reaction above, given that the total pressure is $0.63$ bar.
My calculations:
$0.63$ = p(CO$_2$) + p(NH$_3$)
, where ...
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Pressure vs electric conductivity in solids
If we apply pressure to a solid, does it change its electric conductivity? I am asking this because in 2020 they announced a superconductor at room temperature but under a pressure of 3/4 of the ...
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Find gas pressures of injection knowing mixture pressure without knowing volume
Let's say we have a gas 1 moving inside a pipe (we don't know the geometry) at mass flow rate $Q_1$ and temperature $T_1.$ We inject a gas 2 at some point inside the pipe with gas 1 at mass flow rate $...
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Finding rate constant from a change in pressure experiment
I measured the change in pressure for the decomposition of hydrogen peroxide in the presence of a manganese(IV) oxide catalyst at 5 different temperatures:
$$\ce{2 H2O2 (l) ->[MnO2 (s)] O2 (g) + 2 ...
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How does hydraulic equilibrium work on the particulate level?
I recently learned that osmosis occurs when there is a semipermeable membrane between pure water and a solution of water. The pure water then fills up the solution's side until, as my textbook put it,
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Help with two containers problem, Xenon
In two containers we have Xenon. The volume of the first container is 2780 L, temperature is 300 degree Celsius, and n = 200 mol. Volume of the second container is 4000 L, temperature is 1300 degrees ...
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Finding equilibrium constant for the reaction between non-stoichiometric mix of gaseous components
$$\ce{CH3OH(g) + NOCl(g) <=> CH3ONO(g) + HCl(g)}$$
The volume of the container is $\pu{433 cm^3},$ $T = \pu{50 °C}.$ Methanol was added until the pressure was $\pu{50.1 mbar},$ then $\pu{0.059 g}...
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Confusion in barometer experiment
Now at A, there is pressure by mercury column which is nothing but it's weight. Then, at C there is pressure which is atmospheric pressure. Also, the density at A is more than at C. What they say ...
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Do most chemical reactions happen at constant pressure?
While studying enthalpy $H=U+PV$ and its changes, I realized I am not clear on the following: chemical reactions happen with the external pressure being constant and equal to the atmospheric pressure $...
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Work done by system of ideal gas in isobaric expansion
Consider a system of ideal gas in a container with piston and the isobaric expansion of gas takes place.
As the process is isobaric, so initially the pressure of gas is equal to atmospheric pressure ...
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Volume of compressed helium gas needed for FE test on ball valves
I'm currently doing a case study to find out the exact volume of helium gas required for FE tests on ball valves regards to the valves' volume and pressure class and the number of helium tanks needed ...
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Can I mix pressures and concentrations when finding equilibrium constant? [duplicate]
In order to find the equilibrium constant (or reaction quotient) I know I can find the value as the products over reactants raised to coefficient exponents. But, in all of the problems I have had to ...
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Can you make n-Hexane a supercritical fluid? [closed]
When making aerogel using supercritical fluids the liquid in the gel is replaced by a gas. Can this be achieved using n-Hexane as the supercritical fluid? What would the resulting gas be? Would it be ...
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Manufacture an artifact with compression
Room-temperature superconductivity has finally been demonstrated, as reported by Quanta (and others), with the caveat that it requires compression of the substrate at nearly 2 Mbar. Obviously, this ...
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Work done on a Gas?
I'm extremely confused about work done on a gas. So if you look at the system pictured,
From what I've read online, the net work done, which is equal to the work done by the objects, is equal to the ...
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Ratio of rates of diffusion of gases
I stumbled upon a question, A mixture of 50 mL of Hydrogen gas and 50mL of Oxygen gas is allowed to effuse through an effusimeter. After some time it is observed that the residual gas occupies 90mL. ...
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If I hard boil eggs in a pressure cooker, will I get the same results regardless of altitude?
This seems like it should be obvious but for some reason (my chemistry is very rusty) I'm having a hard time articulating why the hardboiled egg recipe in an instant pot should yield the same results ...
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Is there more efficient reaction for generating hydrogen rather than HCl+Al [closed]
I want to generate hydrogen to acquire known pressure inside of an object.
I have calculated required mole number for hydrogen using the ideal gas equation by giving wanted pressure, volume and ...
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At what pressure will hydrogen start to liquefy at room temperature?
I want to increase a fixed-size object's internal gas pressure by generating hydrogen in it, but I could not find the proper phase diagram for it. So I am wondering how high pressures I can get.
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Is is valid to compare reaction quotient to $K_p$ as well as $K_c$?
Can I use the reaction quotient compared to $K_p$ to answer the following question?
The solid $\ce{XY}$ decomposes into gaseous $\ce{X}$ and $\ce{Y}$: $\ce{XY(s) <=> X(g) + Y(g)}$ with a $K_p = ...
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Textbook problem with molar mass of carbon dioxide
$\ce{K2CO3}$ and $\ce{HCl}$ react to produce $\ce{CO2}$. In an empty flask ( m = $\pu{85.431 g}$ ) we put in the produced gas and the mass of the flask is now $\pu{85.510 g}$. After that we fill the ...
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At what pressure is the triple point of ethane?
Depending on source there are two givens for the triple point of ethane: 0.8 Pa or 1.1 Pa. Only one of them can be correct, which one is?
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Effect of pressure on gas solubility in liquids
By Henry's Law ($K=\frac{x}{p}$), we know that increasing the partial pressure of a gas also increases its solubility on liquids.
Now a lot of sources (this, for instance) illustrate this by ...
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What gas law is involved when your ears "pop" when you are on a plane high in the air? [closed]
When you are up in the air, the air pressure decreases and the altitude increases. What gas law is involved in the situation wherein your ears "pop" because of the difference in pressure.
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Effect on mass when decreasing pressure in equilibrium reaction
For example, if we have the reaction:
$$\ce{A + B <=> C}$$
And the volume is decreased, the pressure would increase. Hence, according to Le chatelier's principle, the system will partially ...
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Misconception of gas laws [closed]
I face a misconception with gas laws: Boyle’s law, Charles’ law, and Gay-Lussac’s law.
This is because each law of these assumes the constancy of one of the three following variables (the pressure, ...
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Can work be done on a body when temperature and pressure are changed without changing its volume?
Can work be done on a gaseous system when temperature and pressure are changed without changing it's volume?
In chemistry the formula of work is always $p\,\mathrm dV,$ whereas we can also do work on ...
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Changing pressure on equilibrium
Recently I heard my teacher say that when increasing the total pressure of the system, the reaction which is "more dependent on collisions" is favoured.
This seems to make sense, although I'...
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Can silicon dioxide melt at 20 °C?
Can $\ce{SiO2}$ melt at $\pu{20 ^\circ C}$?
I have searched the web for $\ce{SiO2}$ phase diagram, but it seems to me that almost all the graph I can find have the temperature axis where the minimum ...
