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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Using Le Chatelier's Principle to Change Mechanical Energy to Chemical Energy

I was interested in an application of Le Chatelier's principle, where an increase in pressure could result in a decrease in the moles of gas. In particular, a situation where when the pressure ...
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3k views

Effect of temperature and pressure on structure of solids

What is the effect of these conditions on the structure of solids? My book has the answer that confuses me. I got nothing about it. Can you please explain? The answer of the book is With the ...
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41 views

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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31 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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70 views

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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88 views

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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0answers
53 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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2k 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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87 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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47 views

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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1answer
89 views

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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1answer
40 views

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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944 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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25 views

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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45 views

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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25 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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20 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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1k 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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28 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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36 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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88 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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32 views

Calculating Gas Pressure with Water Vapour

$\pu{4.0 L}$ of oxygen was collected by the displacement of water at $\pu{105.0 kPa}$ pressure and $\pu{30 ^\circ C}$. If the vapour pressure of water at $\pu{30 ^\circ C}$ is $\pu{4.2 kPa}$, ...
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245 views

Is brass combustible in high pressure oxygen environment?

Some metals are particularly ignitable in high pressure oxygen environments, like stainless steel and aluminum. Copper and nickel, on the other hand will self-extinguish when ignited. Does anyone know ...
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169 views

Pressure increase due to the reaction of CaO and HNO3

Currently I'm facing difficulties in determining the pressure increase due to the reaction between $\ce{CaO}$ and $\ce{HNO3}$. To be more specific, we first fill a vessel with $\ce{H2O}$ and $\ce{CaO}$...
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48 views

Pressure/ vacuum on preciptation of a borax saturated solution

Trying to go back to my collage chem/physics. We put a supersaturated solution of borax on the stove. (heated water, added borax till it would not take more borax). Placed them under vacuum 15 inhg,...
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118 views

Find Equilibrium Constant with only balanced equation?

Calculate the value of $K_p$ for the following equation: $$\ce{PCl3 (g) + Cl2 (g) <=> PCl5 (g)} ,\qquad \mathrm{R = 0.0821 \frac{L\times atm}{mol\times K}}$$ This question appeared on my test. ...
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752 views

How to find pH of an aqueous ammonia solution at high pressures?

Here's the simplified question: I start with $15~\%$ of $\ce{NH_3}$ and I want to find the $\mathrm{pH}$ of the following reaction at $25~\mathrm{^\circ C}$ and $5\ \mathrm{kbar}$: $$\ce{NH_3 + H_2O -&...
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2k views

What is the temperature at which lava evaporates?

According to this article -> http://ntrs.nasa.gov/search.jsp?R=19660041998 Lava evaporates under natural conditions, but apparently, only a little bit. I'd like to know the temperature at which ...
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122 views

How to test acid-base reactions under pressure?

I am trying to test chemical reactions, more specifically reactions between an acid and a base, at different levels of pressure. I would like to know if there is some kind of equipment I can get that ...
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2k views

Why does melting point depend on external pressure?

The melting point of a substance is the temperature at which the solid form's vapor pressure equals the liquid form's vapor pressure. I read that the vapor pressure of something depends ONLY on the ...
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1answer
55 views

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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92 views

Relation between vapour pressure and boiling point

In my childhood I was very happy with the following definition of boiling point The temperature at which a substance changes from liquid phase to gaseous phase is known as boiling point. But with ...
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13 views

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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36 views

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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38 views

Diatomic molecule under pressure

If we put a diatomic molecule under pressure the interatomic distance will be decreased and according to this graph the potential energy of the bonding molecular orbital will be increased. What will ...
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45 views

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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76 views

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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32 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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24 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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26 views

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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48 views

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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24 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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31 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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26 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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134 views

Can every liquid pure substance be compressed to solid?

Apart form the fact that liquid are often misleadingly considered incompressible, fact that I recently find out to be true only as an approximation in specific circumstances. I was curious to know if ...
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349 views

Why doesn't a temperature and pressure gradient exist in a container of real gas?

In the Kinetic theory of gases, it is assumed that there are no intermolecular forces between the atoms/molecules. But real gases, have intermolecular attractive and repulsive forces. Suppose a ...
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277 views

Is OH + CO → CO2 + H an elementary reaction?

Is $$\rm OH + CO \longrightarrow CO_2 + H$$ an elementary reaction? How could I tell? I could break the reaction into $$\rm OH\ (+ M) \longrightarrow O + H\ (+ M)$$ $$\rm CO + O \longrightarrow ...
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152 views

How does Le Chatelier's principle apply to a fuel tank full of hydrogen?

A nano-tube packed fuel tank is full of Hydrogen, and there is a steady pressure of Hydrogen in the tank. While hydrogen gas is being removed from the fuel tank to power the car, the pressure in the ...
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3answers
1k views

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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40 views

What is the theoretical energy density of octaoxygen?

Due to the higher density and stressed bonds, I imagine the energy per gram in octaoxygen is much higher than in conventional oxygen, however the calculations needed to achieve this value is beyond my ...