# Tag Info

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Dissolution(solvation) is solvation of solute molecules by molecules of solvents. This decreases chemical potential $\mu={\left(\frac{\partial G}{\partial n}\right)}_{T,p}$ of the solute, comparing it (often hypothetically ) to the chemical potential of the solute at the same concentration in gaseous phase. Different solvents cause different chemical ...

6

"Sealed in a vacuum" is an oxymoron, a contradiction in terms, much like "frozen with fire". If you seal a liquid in a flask containing nothing else but vacuum, then a part of the liquid will quickly evaporate and fill the flask with vapor, so it would no longer be a vacuum. The said vapor will exert some pressure, depending on the temperature and the ...

5

I found this statement in a paper about $\ce{Hg}$ contamination from dental work: The evaporation rate of elemental mercury at room temperature ($\pu{20 ^\circ C}$) is approximately $\pu{50 \mu g\:cm-2h-1}$ (range of $\pu{40-60 \mu g\:cm-2h-1}$). They cited the following work as a source for that number: Gary N. Bigham, Wanyu R. Chan, Manuel ...

4

During the process of distillation, we condense the vapours (B) of the mixture (A) to give a mixture (C) that has the same mole fractions as that of the vapour (B) of mixture (A). In order to solve this question there would be three steps. Firstly, finding the vapour pressure of the initial mixture. Second, we find the mole fraction of components in the ...

3

I'd like to specifically commment on this: According to the NCERT for Class XII, Part I, [pg. 46, para 3][1], In a pure liquid the entire surface is occupied by the molecules of the liquid. If a non-volatile solute is added to a solvent to give a solution [Fig. 2.4.(b)], the vapor pressure of the solution is solely from the solvent ...

3

For solvent at temperature $T$, surface area $A$ and having the molar fraction $x$, the rate of molecules leaving liquid is: $$\frac {\mathrm{d}n}{\mathrm{d}t}=-C_1 \cdot A \cdot x \cdot f(T)$$ Lower molar fraction means lower surface density and lower evaporation rate per surface area. Factor $C_1$ includes pure solvent molecular surface density and $f(T)$ ...

3

It is valid for both volatile and nonvolatile solutes, as it refers to the partial vapour pressure, not total vapour pressure. Saying that, note that it applies only on mixtures with ideal behaviour, as there are many more or less significant positive and negative deviations from the law. These deviations relate to preference of intermolecular bonding to ...

3

Hm, the proportionality is not so very good. (data from the wikipedia link above) The line is a linear regression through all ten data points. The answer to your question is given on the same wp article. The quotient of enthalpy of vaporisation and temperature is the difference in entropy between the liquid and gaseous phase. According to Trouton´s rule, ...

3

You may look at silicon Si and its derivatives. For example, the ethoxytriethylsilicane, or triethylsilicol ethyl ether is boiling at 153 °C. Or the tetraethylsilicane is also boiling at 153 °C. This last substance is used as a reference in NMR spectroscopy.

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Consider a system with a variable volume (e.g., a syringe, but on a larger scale). As the volume increases, liquid becomes vapor without changing the amount of material present. In a system where there is only one component, changing the volume of the container will change the fraction of material in the vapor vs the amount of material in the liquid. But ...

2

Imagine the converse situation: A sealed chamber has an open beaker of the volatile solute. After some time, equilibrium vapor is established. Now an open beaker of the non-volatile solvent is introduced into the chamber. Some molecules of the solvent in the chamber's "atmosphere" will dissolve into the open beaker of solvent, and that process ...

2

When a substance's multiple phases are in thermodynamic equilibrium with each other the vapor pressure is the pressure exerted by a vapor existing above a liquid surface. Vapor pressure is related to volatility; the greater the pressure above the liquid the easier it is for vapor molecules to escape the equilibrium and transition to the gas phase. A simple ...

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There is not enough information to decide, and the question is not clearly worded. As to the wording, "two volatile solutions (ideal) of pure liquids P and Q respectively," implies there is no vapor present, yet "vapours can travel through". What is the volume of each volatile liquid, and the total volume of the containers, including the ...

2

If you have an initial estimate for the pressure, $p_0$, then you can quickly solve iteritively for the pressure that matches the desired entropy $s=s^*$ using modified Newton's method: $$p_{n+1}=p_n-\frac{s(p_n,T)-s*}{\left(\frac{\partial s}{\partial p}\right)_T}$$The partial derivative of s with respect to p can be obtained by finite difference at the ...

1

Water molecules in gas phase collide and are absorbed by both solutions at the same rate, assuming the same humidity over the solutions. OTOH, as sugar solution has lower molar fraction of water than water itself, its rate of water evaporation is lower than pure water evaporation. Therefore, there is the net transfer of water molecules from the water beaker ...

1

Create a vacuum enduring apparatus, equipped with a heated flask with the solution, with constrained capillary air inlet immersed into the liquid ( provides boiling centers to avoit overheating ) and pressure sensor, attached to a vacuum source. Combination of applied heating and vacuum, there will be established "laboratory grade equilibrium", ...

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You may want to read the Wikipedia article on TMAH. While it does decompose, it may not produce the methanol you are expecting. Also, heat is also involved in this process, so you may need to heat and, in the process, vaporize much of the water to get this decomposition to go. TMAH, in common with many other TMA salts containing simple anions, decomposes ...

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Here's how it works. The fugacity of the liquid at temperature T and total pressure P is equal to the equilibrium vapor pressure at T times the Poynting correction (assuming that the vapor phase behaves as an ideal gas mixture). The fugacity of the same species in the vapor is equal to the partial pressure of the substance in the gas phase. The vapor and ...

1

From what I understand, the boiling point of a liquid is when its surrounding pressure is equal to its vapor pressure. This is backwards. The boiling point is when the vapor pressure of the liquid is equal to the atmospheric pressure. So given the average pressure of 1 atmosphere at sea level water would boil at $\pu{100 ^\circ C}$. However on some ...

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There's no definitive answer to your question. You might want to look up azeotropic mixtures. Essentially, to make an azeotrope, you need a set of liquids with really high deviation from "ideal" behaviour, and at the composition where the deviation is maximum, the slope is zero. At that composition, there isn't much variation in vapor pressure as ...

1

To have 100% relative humidity at constant temperature, 3 conditions have to be met: There must be water source to saturate space with vapour. There must not be present materials absorbing humidity below 100%. There must be allowed enough time to reach saturation. E.g., if there is solid table salt exposed to air, the equilibrium relative humidity would ...

1

Why should decrease when it does decrease ? The gas with liquid vapour, previously in equilibrium with liquid, with suddenly increased pressure: Vapour gets over-saturated and condenses until the saturated vapour pressure is reached again. Gas starts dissolving and gas partial pressure decreases, until the new equilibrium between its partial pressure and ...

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1) If you induce a sudden chance in pressure you will indeed take the system out of equilibrium. Lets consider a closed recipient containing some liquid and some gas above. If you suddenly inject more gas into the recipient, the gas pressure is initially going to raise fast and then going to decrease slowly while part of the gas is dissolving, until the ...

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So that must imply that with increased vapor pressure, the mole fraction of the gas in the solution must increase, but quite the opposite is true. Vapor pressure, or saturation pressure, $P_{sat}$, is different than system pressure, $P_{sys}$. $P_{sat}$ is an intensive property, relative to the compound of interest, while $P_{sys}$ is an extensive property ...

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This is where your logic fails: since the concentration of reactants and products remains the same since B is different from A As soon as you mix two components you change the concentration of both, you effectively dilute all components. Otherwise your intuition is correct. The gases can often be assumed to act independently. This is true if the solution ...

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Assume that the initial temperature is room temperature and neglect the initial amount of acetonitrile in the gas phase. Calculate the equilibrium vapor pressure of acetonitrile at 140 C and compare it with the partial pressure you would calculate from the ideal gas law if all the acetonitrile had evaporated (so that its volume is 100 cc). If the latter is ...

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First, not all gases can be liquefied at room temperature by increasing pressure. If the gas is above the critical temperature, it cannot be liquefied by any increase in pressure; it becomes a supercritical fluid. Supercritical fluids have some of the properties of a gas (e.g. diffusing through fine openings), ans some of liquids (e.g. dissolving solids and ...

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Generally speaking, liquid boils at the temperature, at which its saturated vapour pressure is equal the external pressure. With external pressure going down, boiling temperature goes down as well. When external pressure goes down too much, the boiling point may meat the freezing point of the liquid and the liquid freezes. There is no boiling any more, but ...

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As already noted by Maurice, yes you did liquify a gas under pressure. In fact, the scope of application is so wide that this is equally known as Linde cycle. It is highly possible that you have such an engine at home, either as fridge, or freezer to cool stuff, or as heat pump to warm a home. Regarding propane: equally yes. After banning Freon and other ...

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This problem is sloppily worded and, technically, it is not possible to give a definitive answer based on the information provided. But the missing information is not what you think -- you don't need to know the air pressure in the flask. What's missing are two key pieces: The degree of humidity ("humid" doesn't mean "saturated") and the volume of water ...

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