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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21 views

How to calculate the aqueous solubility of CO2 vs Pressure

I would like to make Na2CO3 react with HCl in a closed fixed volume vessel, and accordingly I'd like to understand how ensuing pressure will affect the equilibrium of my reaction (and to which extent ...
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22 views

Does the pressure increase if the gas molecules disassociate?

Assume that we have a one-liter sample of ozone ($\ce{O3}$) at one bar. If we shine a UV ($\pu{250\\nm}$) light on the sample it will disassociate to oxygen atoms ($\ce{O}$) and oxygen molecule ($\ce{...
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1answer
33 views

Calculating partial pressure equilibrium constant Kₚ given initial pressure and equilibrium pressure

A reaction $$\ce{A(g) <=> B(g) + C(g)}$$ happens in constant volume and constant temperature. The reaction starts only with gas $\ce{A}$ (no $\ce{B}$ or $\ce{C}$) with given pressure $...
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2answers
39 views

Metering Device decreases pressure yet produces saturated liquid?

This question pertains to the change of state of liquid using a Metering Device as the refrigerant enters an Evaporator Coil of an HVAC system: The Metering Device takes liquid and then reduces the ...
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1answer
31 views

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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3answers
50 views

Applying vacuum at the end of a flash chromatography column

I know that flash chromatography uses a positive or pushing pressure to achieve the goal which is separation. Would the same goal be achieved if you had a vacuum on the other end instead of a ...
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21 views

Gas Law - increasing temperature with constant volume held

I've set up a simple experiment to look at the ideal gas laws. My experiment is relatively simple in that I have a metal tube which is capped on one side. I am then pressurising the tube with air to ...
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3answers
44 views

How can equilibrium lie to one side ? Surely it’s not at equilibrium anymore? [closed]

Surely they’re not at equilibrium any more? I understand that a favourable condition can make a reaction in one direction go faster, but then surely either the forward or backward reaction is faster ...
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23 views

Pressure dependent rate coefficient

I am trying to study how the pressure will affect the formation of ozone at around 5 bar. So, I am looking for a simple relation between the reaction rate coefficient and the pressure to use it in my ...
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1answer
35 views

Is vapour pressure a surface phenomenon?

As a fact, I know that vapour pressure doesn't depend on surface area. Does this imply it is not a surface phenomenon also? It shouldn't be as then it would depend on surface area of molecules and ...
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24 views

Find the Total Pressure When the Faucet is Released

Two chambers are connected as shown in the figure. The total pressure of the first chamber that contains Ar and He gas is 98.4 atm. If the faucet is released, find the total pressure. (There's 1 mol ...
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2answers
76 views

Can a reactor be operated at both reflux and above atmospheric pressure?

I'm not a chemist by trade so my experience in the lab has probably not been as in-depth as most of you. I've been tasked with investigating a proposed reaction in which an organic mixture (mostly ...
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24 views

A formula for the refractive index of a gas dependent on temperature and pressure

I am in search for a formula that gives me the refractive index of a gas at a given temperature and pressure. Does such a formula exist? Ideally the solution should have this form: $n_g(t, p) = \...
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1answer
148 views

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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17 views

Finding Pressure of M in a Charge Exchange

Ar (RE = 15.5 eV) is the reagent gas in a charge exchange experiment. If Ar+ reacts with anisole with a rate constant of 2.26x10-10cm3 molecules-1/s-1 and 65% of the Ar ions react in 25 milliseconds, ...
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1answer
357 views

Calculating Equilibrium Partial Pressures Given Kp and Mass

For the reaction $$\ce{AsCl5(g) <=> AsCl3(g) + Cl2(g)}$$ at $550$ K, the equilibrium constant ($K_p$) is $9.81$. Suppose that $3.150 \ g$ $\ce{AsCl5}$ is placed in an evacuated $600$ ml ...
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3answers
145 views

Why does increase in pressure cause a increase in boiling point [closed]

When we increase the atomospheric pressure pressure above the solution , the boiling point of a solution increases. Why does this happen?
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119 views

Volume of dried gas at STP

A $54.0\ \mathrm{mL}$ sample of oxygen is collected over water at $20\ \mathrm{^\circ C}$ and $770\ \mathrm{Torr}$ pressure. What is the volume of the dry gas at STP? By using the combined gas law, I ...
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89 views

What will be unit of volume in V=nRT/p if p is in Torr instead of atm? [closed]

$V=nRT/p$, where $n$ is amount of gas in $\mathrm{mol}$, $R$ is gas constant, $V$ is volume in $\pu{dm3}$, and $p$ is pressure in $\pu{atm}$. What happens to $R$ if $p$ is in $\pu{Torr}$ instead of $...
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3answers
514 views

Why is my solution for the partial pressures of two different gases incorrect?

I have the chemical equation: $\ce{NH4NO3(s) -> 2H2O (g) + N2O (g)}$. There are $12.8$ g of ammonium nitrate, and it decomposes completely in an empty container at $25.00\ ^\circ\pu{C}$ until the ...
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45 views

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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1answer
104 views

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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4answers
203 views

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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1answer
38 views

What is a simple formula to approximate the change in relative humidity as temperature rises/falls?

The moisture-carrying ability of air goes up as the temperature rises. So if I take a volume of air and heat it or cool it (allowing it to expand/contract so the pressure remains constant) how can I ...
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3answers
608 views

Equalization of pressure in heat exchanger

I was solving numericals on Kinetic Theory of Gases when I came across this question Two closed vessel of equal volume contain air at 105 kPa, 300 K and are connected through narrow tube. If one of ...
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146 views

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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2answers
1k views

Does the rate constant depend on pressure?

I have read in some books that when pressure increases, the number of effective collisions increases. Hence, $k$ depends on pressure. Is it true? If so, then why doesn't $k$ depends on concentration? ...
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1answer
369 views

Molar mass of a protein from osmotic pressure

The height of a column of liquid that can be supported by a given pressure is inversely proportional to its density. An aqueous solution of $0.010 g$ of a protein in $10 mL$ of water at $20^oC$ ...
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2answers
75 views

How to evacuate a glass vessel containing powders?

I would like to evacuate a vessel (a glass round-bottomed flask) and which contains a few grams of platinum. However, I am worried about the platinum powder being sucked up by the vacuum. A few ...
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1answer
97 views

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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2answers
140 views

Is it true that an evaporating molecule has the same kinetic energy as a molecule in a pot of boiling water?

A molecule on the surface of room-temperature water shoots off the surface of said water, or in other words, it "evaporates." It does so because it gained kinetic energy ${x}$, and ${x}$ was great ...
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20 views

Up to which temperature and pressure can dendrimers (PAMAM) be stable?

I am preparing PAMAM (poly amido-amine) dendrimer and I want to know up to which temperature and pressure can it be stable?
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52 views

Find the boiling point of a compound given a pressure

I need to find the boiling point (in degrees centigrade) of ethanol on a day when the atmospheric pressure is $780\text{ torr}$. I know that the molar mass of ethanol is $46.07\text{ g/mol}$ but I ...
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1answer
45 views

How to synthesize a material at 2000atmospheres?

I am trying to combine various elments and at high pressure. How to achieve these pressures for a gas and in quantities of at least 1 cubic centimeter.
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24 views

Gas concentrations along the gradient from sea level to deep-sea

Studying scuba diving-related phenomenas I thought about how to estimate gases concentration down the sea. Of course, solubility of gases at, for example, $5$ atm of pressure, can be estimated with ...
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1answer
321 views

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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1answer
76 views

Molecular kinetic interpretation of pressure

Regarding the molecular kinetic interpretation of pressure, we arrive at a point in the $F=\frac{\Delta P}{\Delta t}=\frac{2mvx}{\Delta t}$, that is to say, the force exerted in the shock on the wall ...
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1answer
46 views

Can air inside a high temperature (1300C) Kiln cause an explosion?

I saw many kiln designs that lack an opening for hot\pressurized air to come out , or any pressure valve. But when air is heated to such a high temperature (1300C) inside a closed chamber (the kiln), ...
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740 views

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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32 views

Does the way a reaction with gas moles shifts depend on Q or number of moles on either side of the reaction?

Given a container with the reaction $\ce{C2H4{(g)} + HCl{(g)} -> C2H5Cl{(g)}}$, if we inject $\ce{C2H5Cl{(g)}}$ to the container, what will happen? I thought of this in two different ways and got ...
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1answer
187 views

Will ice be cold or not when formed using pressure? [closed]

We know that ice can be formed either by lowering the temperature of water or by applying more pressure. If we lower the temperature of water the ice so formed will be cool which is obvious. If ice ...
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79 views

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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1answer
79 views

Can heat capacity at constant volume for a gas decrease as temperature increases? [closed]

I found a function for the $C_V$ of a gas which is being heated under constant volume,but the function shows that the $C_V$ is decreasing. I was wondering if this is possible for any gas since I know ...
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72 views

What causes both components of a binary gas mix to condensate at the same time for a given composition

Okay, so recently I encountered the temperature - mole fraction diagrams for binary vapour-liquid equilibrium. For now, I only consider two-component systems where the components are very similar and ...
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1answer
32 views

Can the pyrophoric tendencies of a pyrophoric substance be suppressed in a pressurized environment?

It's common knowledge that the pressure of an environment influences many properties of a substance, like the melting point, boiling point, or triple point. Pyrophoric substances ignite spontaneously ...
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2answers
366 views

Le Chatelier’s principle when pressure of gases increased with the same stoichiometric coefficient

$$\ce{C (s) + H2O (g) <=> CO2 (g) + H2 (g)}$$ What will happen to the equilibrium when the pressure of gases is increased? What will happen to the yield of $\ce{H2}$? Since pressure ...
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3answers
253 views

Pressure dependency in Haber Bosch ammonia synthesis

Haber-Bosch ammonia synthesis reaction: $$\ce{3H2 +N2 -> 2NH3}$$ According to the ideal gas law: $pV=nRT$ where constant volume implies $\displaystyle \frac nV=\frac p{RT}$ Then $\displaystyle ...
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2answers
2k views

Why do gases liquify under pressure?

To my understanding, an increase in pressure (of gases in a container) is proportional to an increase in gases' kinetic energy, and hence temperature. However I read that gases liquify under pressure.....
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1answer
50 views

Pressure-Volume Formula Question

I have a chemistry homework problem that states the following: $6.2$ L of $N_2$ at $0.74$ bar is mixed with a $15.2$ L sample of $O_2$ at $0.35$ bar. The gaseous mixture is placed in a container of ...
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1answer
133 views

What happened to this 10 year old unopened plastic bottle?

A colleague of mine found this unopened Aquarius bottle (non-carbonated drink) that was 10 years past its expiration date. The bottle was collapsed inward which would suggest that the pressure in ...