Boiling point Definition and 128 Threads

Hi, I'm trying to understand how to explain what the molal boiling point constant is, from interpreting the units (using an example) K_b =3,62K*kg*mol^-1 I would say "One mole of particles are heated up by 3,62kelvin per kg?" but something feels wrong abou saying it that way. Can someone...

Homework Statement Liquid X boils at 127C, at a pressure of 10.6*10^5 Pa. Its enthalpy of vaporization is 5000 J/mol. At what temperature will it boil if the pressure is raised to 1.08*10^5 Pa? Homework Equations \frac{dT}{dP}=\frac{l}{T(v_{B}-v_{A})}The Attempt at a Solution It seems so...

Homework Statement Consider 2-propanethiol, shown below. Would you expect its boiling point to be higher or lower than that of 1-propanethiol? Why?Homework Equations 1-propanethiol: 2-propanethiol: The Attempt at a Solution I looked it up, and 2-propanethiol does have a lower boiling point...

Homework Statement I had an issue with a professor a while ago. A question was asked, "Why does water boil at 100°C?". What I believe was the targeted answer was something around "Hydrogen bonds." Hydrogen bonds are a valid answer, I believe also correct enough. For clarity purposes, I...

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...

Greetings to all, I need some help for i understand how to demonstrate fluids boiling point dependence as function of pressure (i.e for main cool agents). Which are the basic equations for to write a general formula? I know that in PHWR type reactor water is at hight pressure to prevent...

Homework Statement Calculate new freezing point and boiling point when 0.47 mol ethylene glycol and 0.14 mol KBr is added to 150g H2O. Express your answer using one decimal place.Homework Equations molality = moles solute/kg solvent ΔTf=i*Kf*m ΔTb=i*Kb*m New bp = ΔTb + normal bp New fp =...

So i just took a final and the question was Arrange the following solvents in order of boiling point. water 2-methylbut-1-ene cyclohexane So the answer was Water>cyclohexene> 2-methylbut-1-ene. I understand by the hydrogen bonding that water is definitely #1. But I can't...

arrange the boiling point of the following compounds methoxymethane,butane,pentane and water I quickly arrange like this butane<pentane<methoxymethane<water but after checking wiki,it should be methoxymethane<butane<pentane<water In my knowledge,methoxymethane is a polar molecule,so i...

If you are at altitude and let's say water boils at 95 Celsius. Pasteurization for an X food product is 30 minutes at 82 Celsius at sea level. Now deductively, should I also reduce my pasteurization temperature to 82-5=77 Celsius to compensate?

I know that the boiling point of water is lower when the atmospheric pressure is less (such as at the top of a mountain), but why is that? Once a water molecule has the energy to escape from the binding forces that keep it with the other water moelcules in the liquid, I don't understand why...

What does the atmospheric pressure have to be to make the boiling point of water 20 C?

Homework Statement You come into lab one day and find a well insulated 2000mL thermos bottle containing 500mL of boiling liquid nitrogen. The remainder of the thermos has nitrogen gas at a pressure of 1.0atm. The gas and liquid are in thermal equilibrium. While waiting for lab to start, you...

Which one has higher boiling point?Methanal or Hexanone?

Can alkenes be cracked or only alkanes can be cracked? Then what would the products be? Like for alkanes a alkenes must always be formed but what about for alkenes cracking? Also, when we boil salt water its temperature is 101.4 degrees. But when performing fractional or simple distillation...

If we add a small amount of heat δq to a liquid at its boiling point Tb, it could either increase its temperature a small amount dT = δq/Cv, or suffer a phase change into vapor. Experimentally, we see that liquids remain at Tb until the phase change is complete, and only then continue...

I am studying for the MCAT and I am having a hard time understanding the rationale for the following question from my review: Q: One of the limitations of using a gas as a shock absorbing cushion is that under high pressure, the gas may liquefy and lose compressibility. Which of the...

Ethanol has a higher ΔHvap than water (43.5 vs 41.3 kJ/mol). But water has a higher boiling point (373 vs 352K). How do we explain this?!

I am trying to get the calculations and the data to match up in lab. The boiling point elevation predicted by the equation does not match up to the one I am getting by direct measurement. What am I doing wrong?

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...

Calculating Molal Boiling point elevation constant! HELP! So here's how I did my problem, but the answer I arrived with is wrong. I need help with this...:cry: Carbon disulfide (CS2) boils at 46.30°C and has a density of 1.261g/mL. When 0.250 mol of a nondissociating solute is dissolved in...

I'm doing a lab and I was wondering how to find the true boiling point of water in a room given the barometric pressure in inches(just the equation). I looked on Google and I couldn't seem to find anything about it.

When impurities was added to the water, it tends to increase the boiling point of the water to 102 degree celcius and lower the melting point of the water to -2 degree celcius! Why this happen? Is it because the impurities tends to absorb the heat supplied to boil the water causing it to take in...

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...

Ethylamine has 2 hydrogen bonds, Acethaldehyde has no one, so why the second has a higher boiling point?

Homework Statement What is the normal boiling point in Celsius of ethyl alcohol if a solution prepared by dissolving 26.0g of glucose C6H12O6 in 285g of ethyl alcohol has a boiling point of 79.1 Celsius? Kb for ethyl alcohol is 1.22( Celsius x kg)/mol . Homework Equations 26g of...

I know that volatility is more or less proportionally related to vapor pressure. If they are directly related, are they any exceptions where a more volatile substance may have a higher boiling point than a less volatile substance?

Of the following substances which has the highest boiling point? H20, CO2, CH4, Kr, NH3 I already know the answer is H20 but I would've initially chosen NH3 because of the nitrogen bond to hydrogen but that's obviously wrong. Is it H20 because oxygen is more electronegative then nitrogen??

Homework Statement a) CH4 -164 C , SiH4 -112 C, GeH4, -90 C, SnH4, ? C. b) H2O ? C, H2S -61 C, H2Se -41 C, H2Te -2 C The Attempt at a Solution a)This was an assignment and the right answer was T= -75 C. I did a graph starting from CH4 to SnH4 and I know this because its going...

Homework Statement The equation for the best fit line was y = - 5307.5x + 19.55. Using the equation of the best fit line, calculate the heat of vaporization and the normal boiling point (in C) of this volatile liquid. (Hint: What is the value of Pvap when liquid boils at its normal boiling...

Now this may seem a stupid question, but as my old dad said there are no stupid questions only stupid answers! I am distilling some liquid which has a boiling point of about 190 C, I have put the liquid under vacuum of -1bar and the liquid now boils at about 160C, I would like the liquid to...

How can an element boil before it melts? I came across this- As - Melting Point 816 C and Boiling Point 615 C. Every other element given along with this element in my book has its melting point lower than boiling point which makes sense to me. I am curious to know what is different about As...

Question: Among the six measurements of the boiling point of a silsicon compound, the size of the error was 0.07, 0.03,0.14,0.08 and 0.03 degree C . Assuming that these data can be looked upon as a random sample from the population given by. f(x; \theta) = 2 (\theta - x) / \theta2 for 0 < x...

Question: Among six measurement of the boiling point of a silicon compound, the size of the error was 0.07,0.03,0.14,0.08 and 0.03 degree Celsius. Assuming that these data can be looked upon as a random sample from the population given by f(x;\theta) = 2(\theta-x)/\theta for 0<x<\theta =0...

How can one calculate the boiling of a liquid at a pressure different from standard temperature? Am trying to do it using the ideal gas equation, (PV)/T=(P'V')/T' Where P is the STP, V is 22.4l, T= boiling point at STP, P'= new pressure, V' is the new volume and T' is to be found. But is...

Boiling point in a vacuum... Gidday, I am as new here as it gets, and I have a question to post. I have been having a (heated) discussion with regards to the temperature that water boils in a vacumm. Given: @ 10in Hg water will boil at 192F. If you had a pressure reading of 29.7in of...

I'm writing up a report on an experiment I did involving liquid nitrogen. I need to state the boiling point of liquid nitrogen (77.36K) in the report, as I've used it in calculations, but I don't know if I should get a reference for it or not. I did use a reference (Wikipedia and Google...

Hi all, for a closed container with water under pressure in it, let's say GAUGE PRESSURE of the container is 101 kPa, what will the boiling point of water in that vessel be? Will it be 100 deg C, or will it be 120 deg C because the ABSOLUTE PRESSURE of the water in that vessel is 202kPa...

Boiling Point H20 @ 600 psi? According to the psychometric chart boiling point of water @ 600 psi is 252 C. I have a chamber with water inside (in forms of weight measured drops). I am purging CO2 at 600 psi in the chamber. After am heating the chamber to 155 deg C expecting the water to...

The experimental boiling point of the NaCl solution is lower than that calculated, assuming that NaCl is completely dissociated in solution. Why is this the case? I'm thinking that this is because some of the Na+ and Cl- ions reassociate for a short time, thus causing the solution to...

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...

Hello! I often read that the boiling point of a liquid is when its vapor pressure is equal to the atmospheric pressure. What I don't understand is why they never take the pressure of the water into consideration? Doesn't water pressure increase as depth increases and wouldn't this have to be...

Is there any catalyst or substance that can do this?

I now know that gas can turn into liquid when condition are met (temperature and pressures) But I wonder, Is these liquid from gas have a boiling point? and since at normal temp (room temperature) these liquid turn back to gas state, dose that mean their boiling point are below zero? For...

1.Why does boiling point depend on weight ? 2.Does the vanderwall force depend on weight ?

Homework Statement Given the following data, determine the heat of vaporization and normal boiling point of ammonia Temp (K): 200 210 220 230 235 Pressure (respectively)(torr): 65.3 134.3 255.7 456.0 597.0 Homework Equations ln(p2/p1)=-deltaH/R(1/t2-1/t1) The Attempt...

In organic chemistry, What causes a compound to be more soluble than others? What causes a compound to have a higher boiling point than others? I think the more molecular mass a compound has, the higher boiling point. However, methoxymethane and ethanol both have the same molecular mass...

Hello all I performed a lab where we put a graduated cylinder filled to 90% with water upside down in a large beaker filled with water and measured the volume of the air bubble inside the graduated cylinder at different temperatures. When I graphed Ln(PH20) vs. 1/T I got a slope of -10412...

find the boiling point of HF according to the following reaction HF(L) --> HF(G) ΔH=7.53 [KJ/mol] ΔSsys=0.0257[KJ/(mol*K)] i used the equation ΔH=-ΔS*T >>T=-ΔH/ΔS >>T=-0.0257/7.53 T=-292.996°K surely this is meant to be positive ? have i used the wrong equation?? which other...