Vapor pressure Definition and 114 Threads

Homework Statement Hi I have a question. Predict which of the solutions below will exert the highest Vapor pressure O2 in HOH NH3 in HOH and CH3OH in HOH Homework Equations I drew them out. So I know that CH3OH HOH exhibits h bonding. So does NH3 HOH I was wondering about O2...

I am having trouble with the relationship between these two. My book says that negative heat of solution forms stronger bonds and lowers vapor pressure and positive heat of solution forms weaker bonds and raises vapor pressure. Shouldn't vapor pressure be higher for negative heat of solution...

When the Clausius-Clapeyron equation for saturation vapor pressure over liquid water is derived via the Carnot cycle, it is usually assumed that there is only gaseous water above the liquid. The other atmospheric gases are neglected. However, in common settings (lake, glass of water...), the...

the book says vapor pressure is independent of atmospheric pressure, if that is the case then why must the vapor pressure of a liquid be equal to the atmopheric pressure for it boils. I pictured atmospheric pressure as a column of air sitting above a liquid and therefore pushing down the gas...

Why does the answer say that vapor pressure only depends on temperature and intermolecular forces substance experiences? I thought external pressure did affect vapor pressure because when you heat a pot of boiling water at higher elevation the boiling point decreases, and vapor pressure...

Is boiling basically a really high vapor pressure?

I think I understand, but I want to make sure. The vapor pressure of a substance is the pressure of the substance evaporating/sublimating at a given temperature and can be calculated using the Antoine Equation. This must be measured at the interface of the substance and atmosphere, or if the...

Homework Statement What is the vapor pressure of benzene at 50.0 C? Benzene's boiling point is 80.1 C and its heat of vaporization is 31 kJ/mol Homework Equations The Attempt at a Solution I don't want to be that guy who just says "I don't know" but.. All I know is that: ln P...

I'm studying vapor pressure and I'm having trouble to understand some concepts. Vapor pressure depends only on the temperature of the liquid in question right? For example, if we have a container with water at 30° C, it doesn't matter the experiment, would it ALWAYS be a vapor phase with...

Hi all, Just have a quick question regarding the measurement of vapor pressure. Firstly, let me explain my scenario. I am carrying-out some measurements of steam condensation in a vacuum. The steam is being condensed in a air-cooled heat exchanger. Initially, I let in a quantity of steam...

Hi all, Just have a quick question regarding the measurement of vapor pressure. Firstly, let me explain my scenario. I am carrying-out some measurements of steam condensation in a vacuum. The steam is being condensed in a air-cooled heat exchanger. Initially, I let in a quantity of steam...

Homework Statement A gaseous mixture containing 0.190 mol fraction of carbon tetrachloride (CCl4) and 0.810 mol fraction of dry air is initially at 62.0°C and 1141 mmHg. If this mixture is cooled at a constant pressure, at what temperature does the CCl4 first start to condense? I already did...

From what I have read so far, the vapor pressure of a liquid is temperature dependent while it is independent of the atmospheric pressure. I am not sure why atmospheric pressure would have no effect of the vapor pressure though. For example, if a highly volatile liquid is placed in a sealed...

Hi I'm currently writing a some software for calculating the effects of differant grades of water on Centrifical Pump Purformance i have be able to calculate all the apropiate Pressures, flows, viscositys, density, and pressure loss effects on the pump purformance where I'm having trouble is...

I'm trying to find the equations or diagrams for two types of Saturation Vapor Pressures: 1) Pw = Saturation vapor pressure at water temperature 2) Pa = Saturation vapor pressure at air dew point My solution: Relative humidity = (saturation vapour pressure at dew point)/( saturation...

I'm not totally sure this topic should be placed in this forum, since it is not specifically solid state. Anyways, my question is simply why is there a correlation between vapor pressure and the boiling point of a substance, I would have thought that the boiling point would be at any...

I know that the vapor pressure of a solvent would decrease with a changing concentration if there was an addition of a solute. However, would the vapor pressure change with a changing concentration of the pure solvent (no solute added)?

I am trying to understand the concept of boiling from a very fundamental perspective. Most textbooks say that: as a liquid is heated, it's vapor pressure increases. When the vapor pressure reaches the surrounding pressure(or atmospheric pressure at that point), then boiling occurs. I agree...

I am trying to understand the concept of boiling from a very fundamental perspective. Most textbooks say that: as a liquid is heated, it's vapor pressure increases. When the vapor pressure reaches the surrounding pressure(or atmospheric pressure at that point), then boiling occurs. I agree...

Can someone explain why bubbles only begin to form when the vapor pressure = external pressure? Since vapor pressure is defined as the equilibrium pressure of the gas in a closed vessel, the connection does not seem obvious.

Hi All, I tried to collected hydrogen gas generated from the reaction between a metal and hydrochloric acid. I put a inverted conical flask in the water, and the generated H2 would push the water out of the flask, and then the H2 was collected. However, I guess there is water vapor mixed...

Air is dissolved in blood and other bodily fluids. As a deep-sea diver descends, the pressure increases and the concentration of dissolved air in the blood increases. If the diver returns to the surface too quickly, gas bubbles out of solution within the body so rapidly that it can cause a...

So, we know that isopropanol is more volatile than water. We know that since isopropanol has a higher vapor pressure (40 mmHg at 23.8 degrees Celsius, whereas water is 17.5 mmHg at 20 degrees Celsius). We also know that isopropanol has a lower boiling point than water. Now, are there molecules...

Homework Statement Hi. I'm working on a lab in which I must find the vapor pressure of water. Data that I know is the temperature of the system, the volume of trapped air (2.35 mL), and the atmospheric pressure (1.024 atm). This means that I have 1.1x10^-4 mol of trapped air. Beyond this, I...

Homework Statement A student found that at 750 torr atmospheric pressure and 0.1 deg C, the corrected volume of the trapped air (in a graduated cylinder filled with water inverted in beaker) was 2.20 mL. Under these conditions, how many moles of trapped air are present? This student then...

Homework Statement An aqueous CaCl2 solution has a vapor pressure of 82.3 mmHg at 50 degrees C. The vapor pressure of pure water at this temperature is 92.6 mmHg. What is the concentration of CaCl2 in mass percent? Homework Equations mass %=(mass of component/total mass)*100%...

hi, I am confused about how the vapor pressure affects the materials growth. Can someone comment on the following : If the vapor pressure of a precursor, let's say N, is high then it will be hard to grow a material containing N because it will be hard to incorporate it onto the substrate...

Homework Statement Hi guys, I'm a little lost on what should probably be a simple question Using the following combustion reaction (C7O2H6)s + 7.5 (O2)g --> 7 (CO2)g + 3 (H2O)l the equation indicates that water produed by the reaction is liquid water not water vapor. Is this correct...

I was thinking about the cause of vapor pressure and thought of how it might work. But I’m not sure if these ideas are on the right track or not. For example water at 373K The fraction of molecules with energy above the heat of vaporization (6.8E-20 J/molecule or about 0.4eV) is about...

The density of toluene is 0.862g/ml at 25C and it's vapor pressure s 28.44 mmHg. At 25C, the vapor pressure of toluene above a solution of C10H8 in 500ml toluene is 27.92 mmHg. How many grams of C10H8 are present in the solution? I first used Raoult's equation to find X. Then I used the...

It's hard for me to find the why,bcz most books only give this without any explanation Is there anyone who knows the exact reason?

I gather the following: - A decrease in atmospheric pressure leads to a decrease in boiling point - Thermodynamics explains this using mathematics - A kinetic theory model can also be used to explain I need to know: - The science behind this occurring. Why does a lower atmospheric...

1. Homework Statement The normal boiling points of benzene and toluene aer 80.1C and 110.6C, respectively. Both liquids obey Trouton's rule well. For a benzene-toluene liquid solution at 120C, with the molar fraction of benzene in the solution equalling 0.68, estimate the vapor pressure...

Homework Statement Calculate the vapor pressure above liquid ethanol at 35 degrees C. The density of liquid ethanol at this temperature is 0.7767 kg/dm^3 and the true vapor pressure is 100 torr. Homework Equations K=P'/P , P'=vapor pressure, P=total pressure Antoine Equation: log P=...

Homework Statement The vapor pressure of water at 25.0 C is 23.8 torr, and the heat of vaporization is 43.9 kJ/mol. What is the vapor pressure (atm) of water at 59.8C?Homework Equations Clausius-Clapeyron equation. ln(P2/P1)=(ΔH/R)((1/T1)-(1/T2))The Attempt at a Solution P2=? P1=23.8 torr =...

Homework Statement Which of the following are true statements ? There may be more than one answer a) Volatility of a liquid increases with increasing temperature b) The equilibrium vapor pressure of a liquid results from evaporation exceeding condensation c) The equilibrium vapor...

I'm working on vapor pressure for my general chemistry class, and I recently came across the curve P=C^(-\DeltaH/RT). I was wondering what the units are for C (or are there no units because it is a constant?) and where I could find a table of values for common liquids (water, ethanol, methanol...

Why does adding salt to water increase the vapor pressure? Does increasing the volume of water increase the vapor pressure?

Homework Statement A handbook lists the normal boiling point of isooctane, a gasoline component as 99.2°C and its enthalpy of vaporization as 35.76 kJ/mol. Calculate the vapor pressure of isooctane at 25°C. Homework Equations The only equation that makes sense to use for me is the...

I'm trying to figure out how an electrolyte affects vapour pressure in a solution. My book (Chang chemistry) only lists the formulas for osmotic pressure, boiling point and freezing point. I guess Raoult's law would be something like: P_{1}=i X_{1} P^{1}_{o} Sorry for not respecting the...

Hello all I completed a lab last week where we filled a graduated cylinder up 90% of the way with water and inverted it into a water bath and then we heated the bath to 80 degrees Celsius then measured the volume of the air bubble as it cooled to 50 degrees Celsius and at 1 degree Celsius...

Hi, I've seen a very very small drop of mercury in a little corner of a laboratory table and it likely dates from a whole year. I've been told that mercury is quite volatile. So I shouldn't have seen this little drop if it really dates from the past year. Looking into wikipedia, I see that...

Homework Statement An open vessel containing water, benzene, and mercury stands in a laboratory measuring 5.0 m by 5.0 m by 3.0 m at 25 degrees C. The vapor pressures are 3.2 kPa, 13.1 kPa, and 0.23 Pa, respectively. What mass of each substance will be found in the air if there is no...

Homework Statement Calculate the vapor pressure of iso-propyle alcohol over iso-propyle alcohol in pure liquid state at 298,15K. Homework Equations A possible equation to solve this problem, I think, would be to use this formula put together by two definitions of free energy. \Delta G...

Why is the vapour pressure lowered when non volatile solute is added to a solvent? What is the physical reason? Also, why do binary solutions freeze over a range of temperatures, not at one specific temperature? Thanks guys, as usual, for sharing the knowledge!:smile:

Homework Statement "Suppose you were to collect 1.0 L air by passing it slowly thorugh water at 20C and into a container. estimate the mass of water vapor in the collect air, assuming that the air is saturated." I don't know where to even begin. at first i thought it had something to do...

Homework Statement What is the capor pressure of a solution containing .15 mol of glucose (C6H12O6) and 1.65 mol of water at a temperature of 60.0C? the vapor pressure of pure water at this temperature is 149.38 torr Homework Equations Ralout's law? P=PoX The Attempt at a...

Homework Statement Benzene, C6H6, has a boiling point of 80 degrees Celsius. The density of benzene vapor in equilibrium with liquid benzene at 50 degrees Celsius is 1.153 g/L. What is the vapor pressure of benzene in mmHg at 50 degrees Celsius? Homework Equations PV=nRt density = m/v...

So, I'm new to astrophys, and I'm having trouble making a model because I don't think I understand an equation. It's a vapor pressure law, and it says it takes the form of log(pressure) = A-(B/T) T is in kelvins, A is 10.6, and B is 13500. Apparently pressure ends up being dynes/cm^2...

The vapor presurre of mercury is 0.00185 mmhg at 25 degree C. A single drop of Hg(0.1 mL) is spilled in a laboratory of dimensions 10m x 10m x3m. Does the entire drop evaporate? What is the partial pressure of Hg in the laboratory? (Use 13.6 g/ml for the density of Hg.) (b) The normal boiling...