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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Can you make n-Hexane a supercritical fluid?

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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25 views

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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28 views

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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88 views

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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3k views

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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2answers
54 views

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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180 views

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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21 views

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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1answer
69 views

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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3answers
56 views

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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53 views

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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723 views

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 ...
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Relationship between the partial pressure $p_J = x_J p$ and the perfect gas law $pV = nRT$

I am currently studying Atkins' Physical Chemistry, 11th edition, by Peter Atkins, Julio de Paula, and James Keeler. Chapter 1A.2 Equations of state says the following: When dealing with gaseous ...
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394 views

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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How does pressure influence the dehydration of salts?

It's well known that the boiling point of a substance increases with pressure. I was wondering if something similar happens with hydrated salts and the temperature at which they dehydrate. I mean, if ...
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51 views

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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75 views

Latent Heat, Vapor pressure and Equilibrium [duplicate]

So after reading about this topic i wanted to share what i learned and i wanted you guys to tell me if what i am writting is correct: A pressure vessel has propane inside and it is pressurized. The ...
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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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1answer
27 views

What is the effect of pressure upon the melting and boiling points of a substance? [closed]

I want to know about the inter-relation between the effect of pressure upon the melting and boiling points of a substance. Can anyone help?
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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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Doubt about definition of boiling point [duplicate]

The definition of boiling point says boiling point is the temperature at which the vapour pressure of liquid becomes equal to vapour pressure of atmosphere. But how does the vapour pressure of the ...
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58 views

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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1answer
72 views

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 ...
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1answer
116 views

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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2answers
53 views

What is the vapor pressure of a liquid if it is not in a sealed container(i.e., a river or lake)? Is it just the atmospheric pressure? [closed]

From what I understand, the boiling point of a liquid is when its surrounding pressure is equal to its vapor pressure. The vapor pressure is the pressure of the gas form of the liquid in a container ...
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79 views

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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How to compute the pressure potential of the fermentation of sugar into carbon dioxide?

I'm doing an experiment to ferment table sugar with yeast to capture the resulting carbon dioxide. Suppose I put $x$ grams of sugar in a closed 1 liter bottle with yeast. How can I compute the ...
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42 views

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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What's the effect of Pressure change in Chemical Equilibrium if any reactant or product is Solid or Liquid?

I am studying La-Chatelier's Principle of Chemical Equilibrium. I got a problem of Pressure change in Chemical Equilibrium. I know that Pressure change If a reversible reaction is in equilibrium ...
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43 views

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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1answer
41 views

Equilibrium: Effect of change in composition and value of Kp, Kc on changing pressure

Di-hydrogen gas is obtained from natural gas by partial oxidation with steam as per following endothermic reaction: $CH_4{_{(g)}}+H_2O_{(g)} \ce{<=>} CO_{(g)}+3H_2{_{(g)}}$ How will ...
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Decarboxylation of THCA during CO2 Extraction of Cannabis

We have a strange problem. We are performing CO2 extraction on cannabis and we are seeing considerable decarboxylation of THCA to THC. We have high quality temperature sensors at the heat exchangers, ...
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146 views

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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128 views

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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membrane for a reverse osmosis desalination experiment

We are second year cram schoolers , we are currently working on a project tackling water desalination by reverse osmosis and are required to do an experience. During the process, we encountered some ...
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how to Find $P_{tot}$ Given that $K_p = 28.5$ and the partial pressure at equilibrium

I have the equilibrium equation : $4KO_2{_{(s)}} + 2CO_2{_{(g)}} \ce{<=>} 2K_2CO_3{_{(s)}} + 3O_2{_{(g)}}~~k_p = 28.5 ~at ~25C$. Given that The partial Pressure of $CO_2$ is $0.191~atm$ at ...
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Finding the partial pressure

So I saw this problem but can't seem to figure out how to get the answer. I got a test tomorrow lol. 41) $\ce{SO2Cl2}$ decomposes in the gas phase by the following reaction: $$\ce{SO2Cl2 -> SO2(g)...
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Impregnating polyethylene with oil using pressure cooker?

I have some polyethylene spiral wrap that I'm hoping to impregnate with citrus oil as an animal deterrent. Wikipedia says that polyethylene plastic will pass through "flavourings" fairly easily. It's ...
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What is the triple point pressure for Gallium?

I have seen various discussions about the triple point of Gallium determined to a very precise value, so precise that it is used as a reference for NIST scales and measurements. However, these ...
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Irreversible isothermal expanison when given final and initial pressure but not external pressure

I'm asking about the second part of the question. So for isothermal, irreversible expansion, w = -Pext *change in volume. I calculated V2 through the fact that p1v1=p2v2 since isothermal. For V2, I ...
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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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How to find the final pressure excerted by a mixture of gasses which are then released from a vessel after succesive fillings?

The problem is as follows: $5\ \mathrm l$ of oxygen at $2\ \mathrm{atm}$ of pressure and $10\ \mathrm l$ of nitrogen at $4\ \mathrm{atm}$ are collected in a vessel of $2\ \mathrm l$ in capacity. ...
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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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270 views

Pressure Vs Volume plot for real and ideal gasses

$$\pmb {\underline {\text {Background}}}$$ 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 ...
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Is the heat for constant pressure the same as for constant volume in the formation of nitric oxide?

In the reaction $\ce{N2 (g) + O2(g) -> 2NO (g)}$ my textbook[1] says $q_v$ and $q_p$ are not the same, without any explanation. I know that \begin{align} \Delta U &= q_p + w\\ \Delta U &=...

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