Questions tagged [pressure]
For questions about gas pressure, or the effect of pressure in general on chemical species, substances, or reactions.
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Pressure-dependence of electrolysis voltage
I'm trying to better understand electro-chemistry, so please explain why this second-kind perpetual motion device won't work. I guess it's safe to assume it won't work one way or another.
There is a ...
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Finding the value of pressure equilibrium constant
Question:
A rigid vessel containing only $\ce{NO2(g)}$ is heated to $\pu{337^{ \circ}C}$ and allowed to come to equilibrium according to the following reaction:
$$\ce{2NO2 <=> 2NO + O2}$$ ...
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Pressure in Ideal Gas Law
In Boyle's law ($p$ inversely proportional to $V$ for constant $n$ and $T$), $p$ refers to the applied (external) pressure on the gas.
However, in the ideal gas law, my textbook says that $p$ refers ...
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Is it safe to use borosilicate lab glass as an autoclave?
I'm attempting to do a one-pot synthesis that requires autoclaving the chemical mixture. I thought this process would be greatly simplified by using the lab glass itself as the autoclave in situ ...
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Can Gay-Lussac's law be observed in the reverse direction?
Gay-Lussac's law states that if you decrease the temperature of a gas at constant volume, the pressure decreases by a corresponding amount. This is easy to carry out experimentally. But in practice is ...
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About the use of pascal or atmosphere in chemistry
I was wondering if there are specific formulae in chemistry for which it is "compulsory" or convenient to use atmosphere (atm) rather than pascal (or even mmHg) as a unit of measurement.
Of course, ...
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Changes in pressure for an equilibrium reaction containing a solid/liquid on one side only
For a reaction where there is only one solid/liquid present, but gases present as both reactants and products (are there any examples of this type of reaction?):
$$\ce{A(s) + B(g) <=> C(g)},$$
...
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Stability of CN molecule
The $\ce{CN}$ molecule has been observed spectroscopically in comets where pressure has been estimated to be as low as $10^{-10}\ \mathrm{mmHg}$. Draw a Lewis structure for $\ce{CN}$. Suggest an ...
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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 ...
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How does the partial pressure of oxygen relate to its concentration in water?
I've read that the partial pressure of oxygen in water will be the same as the partial pressure of oxygen in the atmosphere, but that the saturation of oxygen in water is dependent on factors like ...
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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 ...
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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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Why is gas pressure measured in mmHg?
Pressure can be measured in $\pu{mmHg}$ which is equal to the pressure exerted by a “column of mercury” of a height expressed in $\pu{mm},$ at $\pu{0 °C}$ under Earth’s normal gravity.
Does the ...
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When two containers at different T and P are kept together, will pressure become same or temperature?
Two containers, kept at different temperatures are connected through a stopcock and two different ideal gases at different pressures are filled inside them. Initially the stopcock is closed. When the ...
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How can I generate 250 GPa to create metallic hydrogen?
In the preparation of metallic hydrogen, how does one conjure up such immense pressures?
I mean, I read that something like diamond anvils were used to contain the hydrogen, but now, in accordance ...
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How to find the change in internal energy (q+w) for an expanding monoatomc ideal gas?
If a monoatomic ideal gas simultaneously expands against a constant external pressure and drops in temperature, how do you find the internal energy change?
Known values are: $T_1$, $T_2$, $p_1$, $p_2$,...
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Can you push a liquid and a gas into a container at different pressures?
I have a gas ($\ce{CO2}$ for example) and I want to infuse it into a liquid ($\ce{H2O}$ for example). I need a higher pressure of $\ce{CO2}$ to do this. So I push in water into a sealed container (at ...
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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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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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Entropy as the driving force for osmosis
How is entropy responsible for osmosis and is movement of solvent possible from its higher concentration to lower concentration?
By concentration, I will be referring to the concentration of solvent ...
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Why does the liquid in an Oralmedic stick flow uphill after I turn it upside-down?
I was experimenting with an Oralmedic stick, which is basically a cotton swab with a hollow stick that has liquid medicine inside, and observed something very unexpected. I followed the usage ...
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What pressure is created by the electrolysis of water?
I am interested to know what is a reasonable maximum working pressure I could expect against the evolution of oxygen and hydrogen when electrolysing a typical water electrolyte.
My aim is to make ...
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Doubts on Diffusion/ Effusion of gases at different pressures
Let's start with a question:
"One mole of nitrogen gas at 0.8 atm takes 38 s to diffuse through a pinhole, whereas one mole of an unknown compound of Xenon with fluorine at 1.6 atm takes 57 s to ...
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Calculate the pressure of the gas samples as indicated by the manometer
Part A) Given a barometric pressure of $\pu{764.0 mmHg}$, calculate the pressure of gas sample (a) as indicated by the manometer.
Part B)
Given a barometric pressure of $\pu{764.0 mmHg}$, calculate ...
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Unknown Mass in Dalton's Law of Partial Pressures
An air with mass of $0.454\ \mathrm{kg}$ and an unknown mass of $\ce{CO2}$ occupy an 85 liters tank at $2068.44\ \mathrm{kPa}$. If the partial pressure of the $\ce{CO2}$ is $344.74\ \mathrm{kPa}$, ...
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Calculating the equilibrium constants for parallel reactions
So, I am attempting to calculate the equilibrium constant for two separate reactions.
$$\ce{A + B<=>C + D}$$
$$\ce{A + B <=> C + E}$$
I have figured out the final pressures at equilibrium ...
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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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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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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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What actually happens to the volume of a gas in an isolated system?
In an isolated system with adiabatic walls in which gas is filled what exactly happens? How do we define the volume of a gas here? Is volume of 1 mole of gas present in that inelastic container the ...
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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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what is actually supercritical fluid? [duplicate]
let’s take an example: if we have a glove-box filled with helium at 5 bars at room temperature which is far beyond its critical point, what actually it would be like ?
would it be like a normal gas ? ...
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What does the osmotic pressure do in an electrolytic solution?
I have learnt that in an electrochemical cell, the osmotic pressure in the solution hinders the flow of ions from the electrode to the solution, rather some ions may accumulate on the electrode ...
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Determining the amount of water to create a given pressure in a sealed container
I have a sealed container with a volume of 1 liter. I want to go from an initial pressure of $P_{1}=1\ \mathrm{atm}$ and an initial temperature of $T_{1}=298\ \mathrm{K}$ to a final pressure of $P_{2}=...
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Does osmotic pressure depend on the quantities of the outer membrane solvent?
$$\pi V = nRT$$
What is the osmotic pressure at $\pu{25^oC}$ of an aqueous solution of 0.0010 M $\ce{C12H22O11}$ (sucrose)?
We just need to substitute the data into equation (13.4)
$$\pi = \frac{\pu{...
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Validity of ideal gas law for pure species or mixture
I'm currently dealing with an application involving gases. I have pure nitrogen as a pressurizer and eventually water vapour (only if condition for evaporation or boiling are met).
I wanted to ask to ...
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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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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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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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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 ...
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What value should I use for P in the ideal gas equation for an unknown molar quantity?
I did a chemistry lab, in which baking soda and vinegar were reacted in a ziplock bag, and I was to calculate the proper quantity of reactants to fill the bag with CO2. The molar quantity of gas was ...
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Defining the partial pressure equilibrium concentration
First off, I am not a chemist. I'm an engineer with an interest in thermodynamics for engine simulation for the basis of emissions. So if I have asked something stupid, this will be why.
So I am ...
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Conversion of a permeability value from barrer to SI unit
I have done a permeability experiment on LDPE in the presence of air. At $\pu{30^\circ C}$, the permeability was found to be 1.846 barrer.
Now I am trying to apply this permeability value to a ...
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How do the pressure acting on the reactants and the initial temperature of the reactants affect the enthalpy of reaction?
In an exothermic reaction that occurs under constant pressure, does the pressure acting on the reactants affect the enthalpy of reaction? Does the initial temperature of the reactants affect the ...
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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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How can you achieve negative pressure?
Pressure is the magnitude (absolute value) of the force over the area, so how can that result in a negative value for pressure as would happen in certain circumstances?
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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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How to calculate air tank capacity from tank displacement, tank fill (gauge) pressure, and specific type of gas?
I am trying to calculate the amount of a specific compressed gas that will fit in an air tank of specific displacement, at a specific pressure. This is in reference to compressed air guns.
The inputs ...
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What happens to pressure when a liquid goes supercritical?
Fill a pressure vessel with water, no airspace. Heat it past 374 Degrees C, so that the water goes supercritical but can't expand. What happens to the pressure at that point? Does it continue to ...
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How to derive this temperature-pressure-specific volume relationship?
(for isentropic, adiabatic, ideal gas flow)
$$\frac{T_x}{T_y} = \left(\frac{p_x}{p_y}\right)^{\frac{(\gamma-1)}{\gamma}} = \left(\frac{V_y}{V_x}\right)^{\gamma-1}$$ where $V$ is the specific volume, $...
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