All Questions
Tagged with pressure physical-chemistry
95 questions
5
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Relation between dilution and osmotic pressure
The following question is taken from IAT 2024, an entrance test for research institutes in India at the high school level:
Which one of the following plots correctly describes the variation of ...
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0
votes
0
answers
80
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If a pocket of nitrogen gas is pumped in at the bottom intake of a padded tank will the pocket of gas bubble up?
I have a nitrogen gas padded tank (tank 1) which is filled from the bottom of the tank. Tank has a set point of 30 psi which adjusted as tank level changes. Also at the inlet is an additional pipe ...
- 19
3
votes
1
answer
120
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Effect of Pressure on the Position of Equilibrium
The following general reaction proceeds with decrease in amount of substance, so increasing pressure should shift the position of equilibrium to the right.
$$\ce{2 A(g) <=> B(g)}$$
But let's say ...
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1
vote
1
answer
116
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What is the exact definition of isotonic solutions?
Background of the Question
I am a high school student so maybe my understanding of this topic is quite less, so apologies in case I have asked an elementary question.
My chemistry sir taught that :-
...
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2
votes
1
answer
312
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Are there materials harder than diamond at high pressure?
It is well known that hardness and Young's modulus can change as a function of pressure. Are there any chemical substances that under sufficiently high pressure exceed the hardness of diamonds at the ...
- 317
6
votes
2
answers
851
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Heat capacity of (ideal) gases at constant pressure
I've come across this article which says that the constant pressure heat capacity is independent of pressure.
It also gives a mathematical explanation which says that any work of an ideal gas at ...
- 471
0
votes
1
answer
310
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Is fugacity the corrected pressure that should be used in thermodynamical models?
I am a little confused about fugacity and pressure of a gas. In ideal gases, pressure is same as fugacity. But for real gases this is not the case. Here is the link of the question that is the source ...
- 305
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4
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175
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Which way Le Chatelier's principle
I have been pondering about the effect of pressure change in regard to Le Chatelier's principle on reactions. For this, I considered the following reaction:
$$\ce{CO(g) + 3H2(g) <=> CH4(g) + H2O(...
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7
votes
2
answers
914
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Does high pressure reverse reaction between zinc and sulfuric acid?
When zinc is added to sulfuric acid, it undergoes a chemical reaction that generates hydrogen gas and zinc sulfate. Can this reaction be reversed by applying pressure to the products converting them ...
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-1
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1
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70
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Calculating percentage of Zn in a coin
Question:
An old coin found in an ancient temple is composed of zinc coated with copper. In an experiment to find the percent zinc in the coin, a student determined the weight of the coin to be 3.0 g. ...
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3
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1
answer
274
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How does pressure affect the color of reaction medium with equimolar amounts or reactants and products at equilibrium?
Chlorine gas is pale yellow-green, and both hydrogen and hydrogen chloride are colorless gases. According to the Le Chatelier's principle, the change in pressure will not affect the following ...
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2
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0
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515
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How to calculate vapor pressure of ethanol at given temperature?
The following is a part of the problem I am struggling with. I think what I need is a vapor pressure of ethanol at $\pu{25 °C},$ but I may be totally wrong.
A reactor is charged with $\pu{60 bar}$ of ...
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0
votes
1
answer
819
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What causes water to condense when air pressure is reduced?
In this video: https://youtu.be/IyBRGhXBuGw
The cabin pressure is reduced and subsequently a mist is formed.
What exactly is the cause?
1
vote
1
answer
530
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Do solids in a solution also apply partial pressure? If yes, can this be used as an intuitive explanation for osmosis?
I know that in a mixture of different gases, we can assign every type of gas molecules a partial pressure so that the total pressure is the sum of all partial pressures. This can be extended to gas ...
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1
vote
0
answers
106
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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 ...
2
votes
1
answer
343
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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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0
votes
1
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550
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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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1
vote
2
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206
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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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5
votes
1
answer
2k
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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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0
votes
0
answers
29
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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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3
votes
1
answer
620
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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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-1
votes
1
answer
60
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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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1
vote
1
answer
205
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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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2
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1
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189
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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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0
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0
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65
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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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1
vote
1
answer
215
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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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2
votes
1
answer
84
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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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0
votes
2
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101
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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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0
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62
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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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1
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2
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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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1
vote
1
answer
294
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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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1
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1
answer
140
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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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3
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2
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296
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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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-1
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3
answers
825
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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 ...
3
votes
1
answer
2k
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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 ...
5
votes
2
answers
902
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Pressure exerted by a particle of ideal gas
There is a step I fail to grasp in the proof that for a monatomic ideal gas, $U=\frac{3}{2}PV$, where $U$ denotes the internal energy of the gas.
The proof involves considering a particle with mass $m$...
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2
votes
0
answers
175
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Measuring vapour pressure in a closed system
My experiment requires the determination of vapour pressure from which I will calculate the number density (or number of moles of the molecule) later, for a closed system.
Here's my setup :
Liquid ...
- 1,582
1
vote
2
answers
142
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Shouldn't the pressure of gas above a liquid slightly decrease when some of its molecules dissolves in the liquid? [closed]
Lets say a liquid and gas above are in equilibrium.
(1) Now if I suddenly increase the pressure of the gas it will take some time for some molecules of the gas to enter the liquid and get dissolved. ...
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1
vote
1
answer
1k
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Why are pressure or volume not able to change the equilibrium constant? [duplicate]
It is stated in my textbook that temperature is the only factor that can change the equilibrium constant. According to the Ideal Gas Law, temperature is dependent on the pressure and volume. Thus, ...
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1
vote
1
answer
2k
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Clausius–Clapeyron equation: shape of phase diagrams makes no sense
I am trying to model the melting point of a substance at varying pressures (ranging from very small to very very large). All I am trying to do is make an equation that relates melting temperature to ...
3
votes
1
answer
449
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Percent degree of dissociation of gas by pressure
I stumbled across the following interesting problem:
Assume that you have started to live on a new planet where standard pressure condition is $\pu{2 bar}$, standard concentration is $\pu{1 M},$ and ...
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2
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699
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How do you manage to liquefy a gas by applying only pressure? [closed]
How can you liquefy a gas by applying only pressure? To increase the pressure of a gas you need a compressor, and when the compressor does work on the gas , it will increase his pressure but at the ...
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1
vote
0
answers
2k
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Determining molar mass of protein from osmotic pressure
A 299 mL solution containing 21 g of a protein in toluene had an osmotic pressure of 0.053 atm at 27 degrees Celsius. What is the molar mass (in g/mol) of the protein?
We can use the formula that
$$\...
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3
votes
1
answer
2k
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Using osmotic pressure to find the molar mass of a compound
Working on-board a research vessel somewhere at sea, you have (carefully) isolated 12.5 micrograms $(\pu{12.5E-6 g})$ of what you hope is pure saxitoxin (a non-electrolyte) from a poisonous (and quite ...
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4
votes
2
answers
726
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Regarding units of water potential and chemical potential
If water potential is nothing but the chemical potential of a given solution, then why do their units differ?
If the unit for the latter is taken as 'Energy per molecule' (which makes sense to me ...
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2
votes
1
answer
82
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Why is so different the temperatures of a compressed gas compared to a liquid/gas mixture of the same fluid and they are both at the same pressure?
Why does $\ce{C3H6}$ gas when compressed (in a centrifugal compressor) comes out with a pressure of $\pu{16 bar}$ and $\pu{90 °C},$ and when it is a mixture of $\ce{C3H6}$ liquid/gas stored inside of ...
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11
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5
answers
4k
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Pressure vs volume plot for real gas and ideal gas
Background
Recently I have been studying about the states of matter and came to the topic of ideal gases and real gases, and the laws related to them. While studying it from my textbook, I saw the ...
user84548
0
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1
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192
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What exactly causes equilibrium to shift when pressure is decreased? [duplicate]
Take the reaction:
$$\ce{N2(g) + 3 H2(g) <=> 2 NH3(g)}$$
If pressure is decreased, equilibrium shifts to the left because it has more moles. I understand the basics of why this is, i.e. due to ...
- 11
2
votes
2
answers
1k
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Calculating partial pressure of carbon monoxide
$\ce{ZnO}$ is exposed to pure $\ce{CO}$ at $\pu{1300 K}$ and the equilibrium
$$\ce{ZnO(s) + CO(g) <=> Zn(g) + CO2(g)}$$
is then established at $\pu{1 atm}$ pressure. The density of the gas ...
- 224
3
votes
1
answer
637
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Isothermal vs adiabatic compression of an ideal gas [closed]
Could someone please explain these specific questions physically (especially the first question!)? I understand the corresponding mathematical proofs, but not the physical reasoning? I have looked ...
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