Questions tagged [vapor-pressure]

This is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system. Apply this tag to questions involving clarification related to vapor pressure.

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14
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2answers
2k views

Vapor pressure and boiling point for solutions in open containers

Question 1: If we have an open container which has water in it and is heated. If there is no lid over the container then how can this water ever boil as there will be no vapor pressure created over ...
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2answers
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How is volatility useful in the production of acids?

Sulfuric acid because of its low volatility can be used to manufacture more volatile acids from their corresponding salts. How does volatility affect the production of acids? Isn't it that sulfuric ...
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1answer
881 views

Will the water at the bottom of the tube boil at the same temperature as the water at the top of the tube?

Consider a long, vertical tube of water, as shown below: Where $P_\mathrm{atm}$ is the atmospheric pressure and $P_\mathrm{bottom}$ is the pressure at the bottom of the tube. The tube is long ...
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1answer
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Vapor pressure of immiscible liquids

I have read that vapour pressure of a mixture of two immiscible liquids is $$P=P^0_A + P^0_B$$ where A and B are immiscible liquids. If they are immiscible, they would form separate layers. Thus ...
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What causes the lowering of vapour pressure in volatile/nonvolatile solvent mixtures?

"Based on Figure 13.18, you might think that the reason volatile solvent molecules in a solution are less likely to escape to the gas phase, compared to the pure solvent, is that the solute molecules ...
4
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1answer
648 views

Detailed kinetic explanation for vapor pressure reduction by dissolved solute?

The following problem was asked in JEE Mains 2020 (Sept 2, Shift 1), An open beaker of water in equilibrium with water vapor is in a sealed container. When a few grams of glucose are added to the ...
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3answers
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Is it possible to boil a liquid by just mixing many immiscible liquids together?

In open air, when vapour pressure reaches 1 atm, boiling takes place. I read that if we add two immiscible liquids together, the total vapour pressure of the 'mixture' is close to $p = p^*_A + p^*_b$,...
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2answers
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When water boils at its boiling point how do we call it as an equilibrium?

On boiling, water becomes a vapor, liquid volume decreases and vapour volume increases. Since volumes are not constant, how do we call it as equilibrium?
13
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1answer
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How does Ostwald-Walker method work?

From searching online I found this: The apparatus consists of two sets of bulbs. The first set of three bulbs is filled with solution to half of their capacity and second set of another three bulbs ...
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4answers
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Reason for the formation of azeotropes

Why is it that some liquid mixtures (that exhibit positive/negative deviation from Raoult's law) form azeotropic mixtures at certain compositions? What is the physical reason behind this; are there ...
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1answer
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Raoult's Law and Mole Fraction

Raoult's Law states that the partial vapor pressure of each component of an ideal mixture of liquids is equal to the vapor pressure of the pure component multiplied by its mole fraction in the mixture....
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2answers
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Why is latent heat of vaporization not exactly proportional to boiling point?

Latent heat of vaporization and boiling point are both chemical properties related to the bond strength of the molecule. In general, the higher the boiling point is, the higher the heat of ...
3
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1answer
276 views

Is the vapor pressure of a liquid dependent on the pressure of the atmosphere in which it is measured?

The figure below shows how vapor pressure of a liquid is measured. Initially the flask is at atmospheric pressure. Then the liquid is dropped in the flask. Once equilibrium is reached, the pressure ...
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Vapor Pressure Paradox

This is quite an interesting situation I had thought of. Consider two beakers, each containing $\pu{180 g}$ of water. Also, suppose one of the two has $\pu{1.8 g}$ of glucose dissolved in it. Let's ...
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Why does decreasing the pressure of the system increase the relative volatility of a binary solution?

In our teaching lab, we were posed with the following question as an exersize: If the boiling points of two compounds differ by $\pu{50 ^\circ C}$ at atmospheric pressure, what will be the effect ...
5
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1answer
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Why exactly does high pressure (72 bar) nitrous oxide's pseudocritical¹ temperature drop so far when oxygen is added to make 50%v/v mixture? (Entonox)

This answer to Can precipitation occur in states of matter other than liquids? mentions the unusual case of Entonox. The effects of temperature on nitrous oxide and oxygen mixture homogeneity and ...
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2answers
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Minimum amount of water in pressure cooker

When cooking I would like to know the minimum amount of water I can add to my 6.2 L pressure cooker, worst case, so without any food. At second ring cooking the pressure is 0.8 bar. I assume I need ...
3
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1answer
138 views

Acetic acid odor while testing CO2 sensor; can it be easily removed, is there a better way?

A friend asked me to help test a hobby-quality $\ce{CO2}$ sensor MG-811 (updated link). It uses a solid electrolyte and should provide a sensitivity of something like -40 mV per decade. I though I'd ...
3
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1answer
3k views

Calculate vapor pressure from volume

For a chemistry lab, I'm required to calculate the vapor pressure of some organic solvents... methanol, ethanol, and propanol, in addition to an "unknown" sample of some solvent. In the lab, we were ...
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2answers
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Is sublimation a property of all substances?

I wonder if sublimation can be done only on certain substances like iodine, or it can be done on all substances. In other words, can sublimation be done, for example, on water? If it cannot, then why?...
3
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1answer
101 views

Can we compare the vapour pressure of solutions whose concentrations and temperature is known?

If we have some solutions, in which we know the temperature and concentration of the solute particles, can we compare their vapour pressures? Original question: Which solution has the highest vapour ...
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1answer
254 views

Is it possible to have only liquid in a closed container?

I recently read an answer by Aman Rusia for this question: Is a liquid in a container always in equilibrium with its vapour? In it, they say that You can't have a container filled with only ...
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1answer
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Is every substance in equilibrium with its vapours?

In one of my previous questions, I got an answer from user Jan: The smell of a compound as we perceive it usually depends on which receptors in the nose will bind the molecule (or not). These ...
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1answer
435 views

What is the connection between vapor pressure and intermolecular force explanations of boiling?

I've had boiling explained to me in two ways, and I'm having trouble understanding how they connect. The first way is that a liquid is held together by the intermolecular forces, and boiling involves ...
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2answers
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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 ...
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1answer
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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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1answer
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Liquefying butane in a freezer

If place a can of pressurized liquid butane (such as a lighter refill canister) into a freezer to get it below its boiling point of $-1\ \mathrm{^\circ C}$, and then release it into a container kept ...
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Will evaporation from two immiscible liquids blow up a balloon?

Consider the following setup: Two immiscible liquids A and B are placed inside a balloon at a temperature where neither one of them boils. The inside of the balloon contains some argon, and the ...