Questions tagged [pressure]
For questions about gas pressure, or the effect of pressure in general on chemical species, substances, or reactions.
309 questions
13
votes
2
answers
3k
views
What is "chemical pressure"?
While reading some publications on solid superconductors, I encountered a term "chemical pressure" a few times, which is usually attributed to the changes of superconducting transition ...
- 38.5k
2
votes
2
answers
3k
views
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 ...
- 4,197
4
votes
0
answers
4k
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 ...
- 159
0
votes
0
answers
457
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 ...
- 1,278
16
votes
4
answers
4k
views
Aside from carbon, what other substances can be made "superhard"?
So diamonds are an allotrope of carbon, that is formed when carbon is put under immense pressure, right? What other elements or compounds can you make into "diamonds", as in more durable, harder ...
- 277
0
votes
0
answers
366
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
$$\rm OH\ (+ M) \longrightarrow O + H\ (+ M)$$
$$\rm CO + O \longrightarrow ...
- 1,012
1
vote
0
answers
190
views
Pressure increase due to the reaction of CaO and HNO3
Currently I'm facing difficulties in determining the pressure increase due to the reaction between $\ce{CaO}$ and $\ce{HNO3}$. To be more specific, we first fill a vessel with $\ce{H2O}$ and $\ce{CaO}$...
- 21
1
vote
1
answer
635
views
Does temperature change pressure in isochoric system?
Consider the following equilibrium reaction:
$$\ce{2 NOCl (g) <=> 2 NO (g) + Cl2 (g)} \qquad \Delta H > 0$$
My textbook has a statement that:
If you decrease the temperature when ...
user43236
0
votes
0
answers
170
views
How does Le Chatelier's principle apply to a fuel tank full of hydrogen?
A nano-tube packed fuel tank is full of Hydrogen, and there is a steady pressure of Hydrogen in the tank. While hydrogen gas is being removed from the fuel tank to power the car, the pressure in the ...
- 495
15
votes
3
answers
10k
views
Why do helium balloons expand in volume as they go higher?
I realize as balloons go higher, the atmospheric pressure decreases, doing less to counteract the force of the gas particles pushing against the inner walls of the balloon. But at the same time, doesn'...
- 343
6
votes
1
answer
22k
views
Entropy and specific heat capacity
I have seen the equation $S(T_2)=S(T_1)+C_p\ln(T_2/T_1)$ where $C_p$ is the molar heat capacity at a constant pressure. I understand that this assumes that the temperature range is sufficiently small ...
- 1,717
5
votes
2
answers
7k
views
How does the partial pressure of gas C change with the change in volume of the container?
Suppose I have the equilibrium in a closed container:
$$\ce{3A(s) + 4B(g) -> 4C(g) + D(s)}$$
What happens to the partial pressure of C if the volume of the container is halved?
I was pondering ...
- 91
1
vote
1
answer
13k
views
Can a liquid turn to a solid by applying pressure?
When pressure increases, volume decreases. If an extremely high pressure is applied to a liquid, is it possible to reduce it's volume to an extent where the molecules are very tight together, hence ...
- 111
2
votes
2
answers
4k
views
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 ...
- 646
2
votes
1
answer
383
views
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 ...
- 1,337
1
vote
0
answers
67
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,...
- 11
0
votes
4
answers
3k
views
Is vapour pressure of a liquid solution constant at a given temperature, no matter the size of closed container and amount of liquid taken?
Does vapour pressure of a liquid solution depend on the size of the closed container, the amount of solution taken, given that, the temperature is kept constant? Or will it change if some extra gas is ...
- 151
6
votes
1
answer
681
views
Are wrinkles\folds in paper reversible by heat, pressure or something else?
I ran into this question on Lifehacks.SE, regarding how to remove wrinkles from a crumpled piece of paper. Suggestions included ironing the paper or placing it under some heavy books for a few days.
...
- 1,410
-4
votes
2
answers
13k
views
How does equilibrium change when pressure is increased? [closed]
What happens to the equilibrium when an increase in pressure is applied to a system with the same number of moles of gas on both sides of the reaction, according to Le Chatelier's Principle?
For ...
- 1
12
votes
4
answers
14k
views
Why do we use the external pressure to calculate the work done by gas
I read in a textbook that in the case when we have a gas in a cylinder fitted with a massless frictionless piston being held with an external pressure $p_1$, and when the pressure is reduced to become ...
user38257
0
votes
2
answers
126
views
Understanding Avogrado's hypothesis
I have read that gases under identical conditions of temperature, pressure, and volume contain the same number of molecules, but every gas has different types of atoms so their force of attraction is ...
15
votes
2
answers
334
views
Does exotic potassium exist?
I was reading a book called 'Hundred and Seven Stories of Chemistry'.
There is a chapter about how the attributes of different elements can change in presence of enormous pressure and temperature. ...
- 2,331
1
vote
0
answers
125
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. ...
- 21
0
votes
1
answer
2k
views
Osmotic pressure of a solution of a protein?
A small protein molecule, code-named "sloth", has a MM of $\mathrm{1.50 x 10^4}$ g/mol. What is the osmotic pressure exerted at $\mathrm{24.0^oC}$ by 25.0 mL of an aqueous solution that contains $\...
- 21
1
vote
1
answer
436
views
What is pure oxygen (gas) density as a function of T or P?
I'm looking for a set of data (ideally graphed) of $\ce{O2}$ density as a function of $T$ or $p$ (with constant $p$ or $T$, respectively).
The best I've found is this 1948 paper which provides an ...
- 3,620
1
vote
0
answers
87
views
Are there pressure driven reactions such that the product remains stable even after it is depressurised? [closed]
High pressure chemistry tend to return compounds with very interesting and unusual bonding structures, such as $\ce{NaCl7}$, metallic hydrogen and $\ce{Na2He}$
However, for most of these, the ...
- 698
1
vote
1
answer
2k
views
Vapor pressure lowering
I have got this problem in my text book,
Consider these three
mercury manometers. One of them
has 1 mL of water placed on top of the
mercury, another has 1 mL of a 1 m
urea solution placed ...
- 237
0
votes
1
answer
832
views
Does a mixture of gases contain equal volume to that of the container they're in? Why?
In my textbook, the derivation of Dalton's Law of Partial Pressure is done by keeping the volume of a mixture of gas in a container constant which is equal to the volume of container itself.
How ...
0
votes
2
answers
1k
views
How was the bottle crushed by air?
In this video, a water bottle is shown to be crushed by the surrounding air.
My understanding:
When the person pours cold water over the bottle which has hot water inside it, the hot water produces ...
1
vote
1
answer
263
views
What is the variation of atmospheric pressure at large heights?
In an approximation (though not a very accurate one), temperature can be assumed constant throughout the atmosphere. The Earth's gravitational field can also be assumed constant (a better assumption).
...
- 151
2
votes
2
answers
413
views
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}$$ ...
2
votes
1
answer
159
views
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}=...
- 21
3
votes
2
answers
456
views
Can I make a container of (kind of) perpetually boiling water?
It's a common school experiment to make water boil at room temperature by putting it in a container and reducing pressure.
I am wondering if it is possible to make a sealed sphere containing water ...
1
vote
1
answer
1k
views
Does lowering temperature of a gas make it easier to compress?
My teacher said that for ideal gases,
the lower the temperature, the lower the kinetic energy of a gas will be, and it will be easier to compress the gas.
Using the ideal gas equation $PV=nRT$, if ...
- 1,889
1
vote
1
answer
734
views
Change in internal energy of a gas upon expansion against a constant external pressure
I have a question about the following problem which I got wrong:
During expansion of its volume from $\mathrm{1.00\,L}$ to $\mathrm{10.00\,L}$ against a constant external pressure of $\mathrm{2.00\,...
- 69
3
votes
1
answer
11k
views
How to find the molar mass of a compound given mass, vol, temp, and pressure?
A $2.1\ \mathrm g$ sample of a liquid vaporizes and exerts $120\ \mathrm{mmHg}$ pressure at $1.5\ \mathrm L$ volume and $80\ \mathrm{^\circ C}$ temperature. Find the molar mass of the gas.
I first ...
- 31
3
votes
4
answers
2k
views
Enthalpy of a reaction changes with temperature, does this mean bond strengths change with temperature?
During chemical reactions, the bonds between atoms break or form to either absorb or release energy. The result is a change to the potential energy of the system. The heat absorbed or released from a ...
4
votes
2
answers
2k
views
Henry's law and O2 concentration in alveoli blood
Can Henry's law be applied to find $\ce{[O2]}$ in alveoli blood? This kind of question appeared in an another forum and I've been struggling to find a definitive answer. My initial thought was 'no', ...
- 219
6
votes
3
answers
3k
views
Will supercritical nitrogen stay supercritical if we raise temperature and pressure high above critical values?
Nitrogen's critical temperature is -146.96 °C and critical pressure 33.96 bar. If we maintain nitrogen at 220 bar and 400 °C, what will be the state of $\ce{N2}$? Will it be still supercritical? I ...
- 79
3
votes
2
answers
733
views
Is pressure equalization "diffusion"?
There is another question on the site which is:
Two containers, A and B, connected by a closed valve were evacuated and the Chlorine gas (Cl2) with a pressure of 200kPa was put into A and Oxygen (...
- 22.4k
4
votes
1
answer
1k
views
Why do gases under low pressure conduct electricity?
In J. J. Thomson's cathode ray experiment, he used a discharge tube in order to make the gas inside conduct electricity.
Why do gases under low pressure conduct electricity?
- 41
0
votes
1
answer
161
views
Vacuum at different altitude
I have tried to find this searching the internet and I am not sure if I understand it. I want to turn water from solid to gas without going into the liquid phase - Sublimation.
The altitude above sea ...
- 1
1
vote
1
answer
938
views
Van der Waals pressure
I was solving some problems and I had a doubt a problem since the resulting pressure gives me a negative value. The problem was the following:
Could $100~\mathrm{g}$ of $\ce{N2}$ in a $200~\mathrm{...
- 111
3
votes
3
answers
5k
views
Gaseous State(Dalton's Law)
Why does the mixture of gases $\ce{NH3}$ & $\ce{HCl}$ not obey Dalton's Law of partial pressure at room temperature?
Also, what other mixtures don't obey Dalton's Law of partial pressure
1
vote
2
answers
6k
views
The effect of pressure on boiling point?
My textbook states the following:
Qualitatively, I understand why the boiling point of a substance increases when the pressure is increased. However, I learned that if the pressure is increased when ...
user33789
3
votes
2
answers
5k
views
Van der Waals real gas equation
Van der Waals corrected the ideal gas equation for real gases and gave the following equation:
$$\left(p+\frac{an²}{V^2}\right)\left(V-nb\right)=nRT$$
I’m very confused about one aspect of this ...
user33789
1
vote
0
answers
780
views
How to find pH of an aqueous ammonia solution at high pressures?
Here's the simplified question: I start with $15~\%$ of $\ce{NH_3}$ and I want to find the $\mathrm{pH}$ of the following reaction at $25~\mathrm{^\circ C}$ and $5\ \mathrm{kbar}$:
$$\ce{NH_3 + H_2O -&...
- 11
4
votes
3
answers
2k
views
Why do some reactions require specific pressures to happen?
For example, carbon monoxide reacts with hydrogen to synthesize methanol in the presence of some catalysts, but the pressure needs to be $\pu{50 atm}$ and the temperature needs to be $\pu{523 K}$.
...
- 590
3
votes
2
answers
5k
views
Work done on a container, resulting in pressure change
Why does pumping gas into a rigid container (causing the pressure and temperature to increase), not mean that work has been done on the container?
Work is given by the formula : W = -P ΔV
If I go ...
- 2,851
3
votes
2
answers
3k
views
How much pressure does Gallium exert when it freezes?
Assuming the liquid Gallium is in a sealed container, how much pressure will it exert on its container when it freezes?
- 39