Vapor pressure Definition and 114 Threads

It’s usually being assumed that points of equilibrium liquid – its vapor is given by a curve in the (P,T) coordinates, and this curve doesn’t change no matter is there another gas in the system or not. For example: if water is put in the empty volume, it will obviously vaporize, filling the...

Vapor pressure is the pressure of the vapor when it is in equilibrium with its liquid. This only happens when the container where the liquid is present is closed. Indeed, when the container is open, this liquid-vapour equilibrium is never reached, because the partial pressure of the vapor (at a...

Relative humidity can be calculated if you know dewpoint and temperature - by formulae such as the August-Roche-Magnus approximation. All methods - all formulae - ignore vapor resistance (perms). Surely scientists/engineers have a way to then, as a subsequent step, bring vapor retarders into...

I think the answer is D because both molecules can hydrogen bond with their OH groups, but the C=O bond in ethanoic acid is polar and contributes to dipole-dipole interactions. The solution says B is the correct answer, because ethanoic acid molecules strongly hydrogen bond so that most...

I'm wondering if I'm on the right track and if anyone is willing to steer me on if not: Equilibrium vapor pressure (EVP—also referred to as saturation vapor pressure) is dependent only on temperature. Outside pressure has no bearing. Now, of course, with lower external pressure (atmospheric)...

I am wondering about the impact of the hydro static pressure of a fluid on its boiling point. The simplest real world example scenario I can think of is the rate/onset of cavitation at a large depth vs a shallow depth. As we increase the submarine propellor speed to a speed where the adjacent...

Step 1: Values are from textbook 'Building for a Cold Climate' Mbrick = 46 ng/s*Pa*m^2 Mgypsum = 2870 ng/s*Pa*m^2 (for 9.5mm) took the above value and used ratios to determine permeance for 10mm Gypsum board (2870/9.5 = X/10) Mgypsum (new value) = 3021.05 ng/s*Pa*m^2 Step 2...

I have been reading the book "Nanostructures and Nanomaterials" by G. Cao and Y. Yang, and was intrigued by the following passage in page 33: "Assuming the vapor of solid phase obeys the ideal gas law, for the flat surface one can easily arrive at: μv − μ∞ = −kTlnP∞, where μv is the chemical...

when butane lighters are refilled by external canister, HOW and WHY butane gas flows from canister to lighter Is it due to GRAVITY or VAPOR PRESSURE? If GRAVITY is the reason I have posted a link where torch is held above the canister? If it is vapor pressure, it is going to be same is both...

Hello everyone, before I start I just want to mention that I am not an expert in physics whatsoever, so please be as specific as you can get if you wish to provide an answer. (The question itself might be considered stupid to be honest) I read the definition of the boiling point recently and...

Homework Statement There is a picture attached showing the entire problem. Equation 2.78 is the Clausius Clapeyron equation. Homework Equations Clausius Clayperon equation. L = L'T (since there is a linear dependence on temperature) The Attempt at a Solution $$ \frac{de_s}{dT} =...

If I were asked to calculate the vapor pressure, and I calculated the osmotic pressure and converted it to mmHg, Would I get the right answer?

Hi, I'm trying to do some figuring on vapor pressures. If one were to take two plates heated to 220F and press water between them in a press that exerts 100psi, what would the resulting vapor pressure of the water be? Now, what temperature would you heat the plates to if you were using a press...

Hi, We have seen water boiling at low pressures (vacuum jars), Will Oil also boil the same way in vacuum jar? Dilip

Hello, I am working on a project that involves burning a mixture of propane and air under pressure to propell a projectile. This has been done by many people including myself in the past at pre ignition pressures of up to around 10 ATM. However I want to take it a step further and attempt a...

I was reading an online chemistry textbook that said "when a liquid is subjected to hydrostatic pressure (for example, by an inert, non-dissolving gas that occupies the vapor space above the liquid surface), the vapor pressure of the liquid is slightly raised." (link...

Homework Statement Calculate the vapor pressure of water at 25°C, based on the Gibbs free energy when vaporising from liquid water to vapor (so at 1 atm and 25°C ). Homework EquationsThe Attempt at a Solution After integrating d g/d p= RT/p. I get my formula p = p0*exp (-delta gm(p0, T)/RT). I...

Hi There, I am trying to understand if I have a vacuum in the below scenario or simply just really low pressure. A pump supplies a pipe with a constant supply of water at one end (Point A) the water discharges several kilometers away at some lower elevation (Point B). At "Point A" a valve...

Say I have got a super cooled cylinder of half hydrogen and half helium. This cylinder has a pressure of 100,000 Pascal's. At this pressure, hydrogen boils at 20 Kelvin and helium at 4.21 Kelvin. I hope to separate helium by cooling gas down to 4.21 Kelvin but I know that even at the...

A QUESTION. Suppose I enclose water within a large noncombustible substance, say a block of concrete. The water is completely enclosed and sealed = no way for it to escape. Now, I heat the block. I get it very hot. At any temperature I can raise it to, will it still be just water at the...

I am somewhat confused by what pressure refers to in a phase diagram? In a closed box it makes sense to me that the vapor pressure would eventually equilibriate at a pressure determined by the temperature. However, say you have an open box. It makes sense that the liquid would boil when the...

CASE1: A container with some water is open to atmosphere, pressure is definitely atmospheric, no somehow I put cover over it and sealed it also. Pressure would increase because new equilibrium will establish between water and its vapour so pressure will increase in the closed container. CASE2...

What I know: Below link is about Torricelli's law. Velocity of liquid coming out of bottom of the tank i.e comes after using Bernoulli's equation square root of (2*g*h*) where "h" is height of fluid in the container and "g" is acceleration due to gravity...

When we mix water and kerosene, what is the vapor pressure of the mixture? Is it just that of kerosene, or an average of vapor pressure of both liquids? (Kerosene floats on top of water which is why I felt like asking this question)

Partial pressure must be less than or equal to the vapor pressure if there is no liquid present. However, when both vapor and liquid are present and the system is in the phase equilibrium, the partial pressure of the vapor must be equal to the vapor pressure and system is said to be saturated...

I straggle with getting full grasp of concept for Cavitation. I was finding statement that : If The pressure of fluid is lower or equal to the Vapor Pressure then it will start to boiling. And I can't understood the reason behind this. Why actually it happens? I understood where we came to the...

I have searched about this topic all over the internet and non of them seem to explain how vapor pressure is equal to atmospheric pressure. All I need is some forces diagrams and some explanations. How when we increase the vapor pressure it makes the liquid boil faster? Isnt the vapor pressure...

Homework Statement : As the picture shows, there are two NaClaq solutions. One is saturated while the other is not and both of them are at the same temperature. There are three questions asked: a) Above which solution is the vapor pressure of water, PH2O, greater? Explain. b) Above one of these...

I learned that vapor pressure is defined in a closed system, but some questions ask me to consider vapor pressure in an open system. How is vapor pressure defined exactly? And where is this pressure acting against? Also why is it that at the boiling point, the vapor pressure and the atmospheric...

Hello to everyone. I would like to ask a question: I'm analyzing the properties of CO2 for a project and I have noticed that for temperatures between 220 -300 K the Clasius Clapeyron curve is linear on 1/T, that is in the Antoine equation of the form logP = A-B/(T+C), C is almost 0. In my...

I am working on a DIY project and want to understand the system/mathematical model of a traditional steam espresso machine. How I have started to think about the problem is a closed container with liquid and gas. At room temperature I know the vapor pressure of the water. As I increase the...

Homework Statement Benzene and toluene combine to form an ideal solution. At 80 C, vapor pressure of pure benzene is 800 mmHg and the vapor pressure of pure toluene is 300 mmHg. If the vapor pressure of the solution is 400 mmHg, what are the mole fractions of benzene and toluene? (A) 60%...

Homework Statement Some KCl is dissolved in water at 25°C, where it completely dissociates. The vapor pressure of pure water at 25°C is 28.3 mmHg. Estimate the mass in grams of KCl needed per liter of pure water to reduce the vapor pressure of water at 25°C by 5%. Homework EquationsThe Attempt...

Vapor pressure in closed container is well understood by me.But in closed vessel ,it is a nightmare for me.However, in an open container (e.g. pot on a stove) equilibrium cannot be reached due to the vapor being dispersed into the atmosphere .The definition of boiling is when vapor pressure...

Vapor pressure possible only in closed system? b.p is when vapor pressure become equal to atmospheric pressure in which system closed or open ?

Homework Statement There are expanded 0.90kg/s of steam at constant pressure from 3MPa and 70% quality to a final state. If the process is nonflow for which W = 121.3kJ/s, find (a) The final temperature, (b) Q, (c) the available part of Q for a sink temperature of to = 27 Celsius Answers : a)...

This is for "ammonia". The problem says that ammonia is a gas at room temperature. And that this tells us: "the fact that ammonia is a gas at room temperature tell us that vapor pressure of ammonia must be greater than atmospheric pressure". I know that for water, when the boiling point is...

I have recently been reading about vapor pressure and my mind's already blown. I just want to listen from you guys what is vapor pressure in a simple manner. I want to know where is it's direction. Towards the liquid. Let's consider an opened bottle of water which doesn't seem to evaporate at...

Homework Statement If the boiling point is the point at which vapor pressure > atmospheric pressure, so all of the water molecules can break free and fly into the atmosphere (i.e. overcoming the atmospheric pressure), then why is it that when atmospheric pressure > vapor pressure, the...

Homework Statement The following link shows the variation of vapor pressure with temperature. In which way the data should be plotted to obtain a straight line? http://www.chem.purdue.edu/gchelp/liquids/vpress.html The Attempt at a Solution For this, I need to know exactly the...

Hi, I understand that vapor pressure is independent of initial pressure, and depends only on temperature. However, is this true of a non ideal gas at high pressures? (I am specifically interested in the vapor pressure of a meg/water mixture at approx. 100 bar), Thanks

I've been confused about this for a while now and haven't found anything that directly addresses this problem. Please correct any faults you see in my reasoning. My understanding of vapor pressure is that it is the pressure exerted by the vapor phase of a substance above the liquid phase...

Hello all, The question given is: Mercury and many of its compounds are dangerous poisons if breathed, swallowed or even absorbed through the skin. The liquid metal has a vapor pressure of 0.00169mmHg at 24 degrees Celsius. If the air in a small room is saturated with mercury vapor, how many...

Homework Statement A 425-mL sample of hydrogen is collected above water at 35°C and 763 torr. Find the volume of the hydrogen sample when the temperature falls to 23°C, assuming the barometric pressure does not change. (vapor pressures of water : at 35°C, 42.2 torr ; at 23°C, 21.1 torr)...

Homework Statement If 5.00 mL of liquid carbon tetrachloride (CCl4, density = 1.587 g/mL) was injected into a sealed 5.00 L flask at 30.0°C, what volume (if any) of the CCl4 would remain as liquid after equilibrium is reached? (the vapor pressure of CCl4 at 30.0°C is 143.0 mmHg) Homework...

Homework Statement The vapor pressure of pure water at 45 degrees C is 71.9 mm Hg. What is the vapor pressure when 18g of sucrose (MM = 342.3g/mol) is added to 82g of water? Homework Equations VP of solution = mole fraction of solvent * VP of pure solvent The Attempt at a Solution...

Homework Statement http://i.minus.com/juL6gvGzvWdm.png Homework Equations Raoult's law: Pressure of solution = Mole fraction of solvent multiplied by vapor pressure of pure solvent. We're assuming non-volatile solutes. The Attempt at a Solution My solution...

Hi all, I am wondering about where the vapor pressure curve would be located on the PVT surface of a substance. I know that as the temperature of a liquid increases, its vapor pressure increases. This continues until the vapor pressure is equal to the atmospheric pressure, at which point...

In reference to the graph at the bottom, my textbook has a statement '''..A process of vaporization or condensation at a constant temperature is illustrated by the lines G-H-I or I-H-G, respectively, in figure 16.3. Water would vaporize or condense at a constant temperature as the...

Hi, could someone please tell me if the vapor pressure should be combined with the air pressure in a sealed vessel to give the total pressure? For example, if I put room temperature water in a test tube (at sea level) with some head space for air and then seal it, the pressure inside would be 1...