Boiling is the rapid vaporization of a liquid, which occurs when a liquid is heated to its boiling point, the temperature at which the vapour pressure of the liquid is equal to the pressure exerted on the liquid by the surrounding atmosphere. At sea level the boiling
point of water is 100 °C or 212 °F but at higher altitudes it drops to correspond with decreasing atmospheric pressures.
Boiling water is used as a method of making it potable by killing microbes and viruses that may be present. The sensitivity of different micro-organisms to heat varies. But if water is held at 100 °C (212 °F) for one minute, most micro-organisms and viruses are inactivated. Ten minutes at a temperature of 70 °C (158 °F) is also sufficient for most bacteria.
Boiling water is also used in several cooking methods including boiling, steaming and poaching.
So I understand that you get boiling when the vapor pressure equals atmospheric pressure so that the vapor within the medium can overcome the atmospheric pressure pressing on the surface of the liquid, but how do the bubbles overcome the hydrostatic pressure from the water above the bubble. If...
Hi all,
I'm a homebrewer and I'm trying to find the boil off rate in gal/hour when using an electric heating element in my kettle.
If I'm using a 5500Watt heating element at 100%, I'm inputting about 312 BTU/min...Using this site and the table for the losses due to evaporation and radiation...
I'm given an expression for the pressure of air with height z, as
P(z)=P(0)e^{(-mgz/k_bT)}
Where m is the molecular weight of air. It's know that the pressure of water varies with height above sea-level due to the variation of the pressure of the air. The excercise is about to show that...
I know that water can be superheated, but my question is more fundamental. What causes water to boil at 100 deg C? I know that there are several factors (atmospheric pressure, nucleation sites, hydrogen bonding, surface tension, etc) but that's not what I'm getting at. I'm interested in the more...
Suppose I have a sealed container of fixed volume containing 3/4 air and 1/4 of some liquid by volume at room temperature (22C). I wish to boil the liquid by applying external heat.
As I apply heat to the container, the pressure inside the container will rise, which will change the boiling...
I have a recipe that begins with sauteing onions in boiling sugar. It occurred to be today that I don't know what the vapor is that the sugar is giving off when it boils. There is no water in the pan at that point (other then what is in the onions). Are the bubbles that I'm seeing actually...
Look at this example.
I understand the reasoning here, in order to save energy one only needs to boil water slightly. But doesn't it also take longer time to boil it the same amount? I'm pretty sure in a given number of minutes, the spagetti will be more ready (more cooked) if it has been...
Hello! First post here, so hopefully I'm not doing anything wrong.
I've hit a dead end with an experiment and could use some additional perspective. I'm in need of material for a 100 mL round boiling flask that has good transparency down to about 140 -180 nm. I originally considered Type 214...
My organic chemistry textbook says that ethers generally have higher boiling points than alkanes because of dipole-diole interactions, but why then does hexane have a higher boiling point than ethyl-propyl-ether? Is this principle then not true for larger alkanes with 5 or more carbons? Diethyl...
If I have a 1.5 kilowatt range can I get 5 gallons of water boiling faster by introducing it to the pot in small increments and waiting for the water that's already in the pot to start boiling before introducing the next increment or would it be the same amount of time if I just dumped the whole...
Hello, my problem is this
It is possible to buy water heaters that provide ‘instant boiling water’ at the turn of a tap. Assume the heater takes in water at 4^{\circ}C and gives out hot water at 100^{\circ} C. Furthermore, assume that the hot water flows out at a rate of 21s^{-1}
How much...
At a high altitude camp in the Rockies, water boils at 95.4°C instead of 100.0°C. A visitor has requested a
soft-boiled egg (usually boiled for 3.00 minutes at 100.0°C). The activation energy for the reaction in question is 453 kJ/mol.
6 marks
egg protein (l) egg protein (s) How long will it...
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...
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...
Hi guys
First time posting on here.
Family and I were having dinner and a discussion came up.
If I need to boil 1000ml of water, would it boil faster if I boil all 1000 ml at once or if I boil say 200ml, wait for it to boil, add another 200 , let it boil and add another 200 till there's...
Homework Statement
https://scontent-b-dfw.xx.fbcdn.net/hphotos-prn1/v/1012733_10201076259690370_236735593_n.jpg?oh=4896ca67a34d3b223b764aba8ed308ab&oe=528A1B57
Homework Equations
http://upload.wikimedia.org/wikipedia/commons/3/34/Phase-diag2.svg
The Attempt at a Solution
Not sure entirely...
"Which statement applies to boiling but not to evaporation?"
Homework Statement
Which statement applies to the boiling but not to the evaporation of a liquid?
A The separation of the molecules increases greatly
B At normal atmospheric pressure, the process occurs at one temperature only.
C...
Homework Statement
The aqueous solution with the lowest freezing point of the following group is:
1) 0.01m MgSO4
2) 0.01m NaCl
3) 0.01m CH3CH2OH
4) 0.008m MgCl2
5) all equal
Homework Equations
Solutions have lower freezing points and higher boiling points than their solvents...
Homework Statement
A boiling water reactor has a mass flow rate of 1266.4 kg/s. The water enters the reactor at 250 °C. It boils at 291.5 °C. It exits the core at 500 °C. The specific heat of water at 7.5 MPa is 4.380 kJ/kg/°C, the latent heat of vaporization is 2357 J/kg and the specific...
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...
When a solid is heated, its kinetic and potential energies increases. Up to a certain point, the kinetic and potential energy is so high that any heating done to it would only increase the potential energy and not the kinetic energy of the solid anymore. When this happens, some of the...
Hello,
This is basic stuff and I feel a bit embarrassed for asking this, but here goes: From what I think I know, evaporation is always happening in a liquid (water, for example) irrespective of the vapor pressure, but boiling only occurs when the vapor pressure is equal or greater than the...
Hi -
I'm a physics newbie so this is an elementary question, but I can't find the answer with a google search.
Water evaporates at a wide range of temperatures, what is the latent heat in the water vapor (in calories or Joules), for example, at 30°C, 60°C? Assume standard atmospheric...
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
Arrange compunds in order of increasing boiling points and explain why.
C2Br6,C2F6,C2I6,C2Cl6
Homework Equations
The Attempt at a Solution
I have C2Cl6 < C2Br6 < C2I6 < C2F6
My explanation is as follows. C2F6 is highest because it has dipole dipole forces...
Just curious,
When my mom was boiling water i saw that the rate of bubbles coming out of water was increasing as time passed.But i want what is the rate of bubbles coming out is proportional to?
And one thing i noticed is that when the gas is shut off the bubbles stop instantaneously.Why is it?
I have recently wondered how water can dry at normal, livable temperatures, but its boiling point is 373.15K. Is there a difference between drying water and boiling it into a 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...
I understand the differences between evaporation and boiling as stated in secondary school textbooks.
But I would like to know, can evaporation occur at or above the boiling point?
I think that, since evaporation is the escaping of high energy molecules, then when the water is boiling, there...
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
I'm stuck on the following problem: A particular liquid boils at 127°C at a pressure of 800 mmHg. It has a heat of vaporization of 1000 cal/mole. At what temperature will it boil if the pressure is raised to 810 mmHg?Homework Equations
Clapeyron's equation...
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
In Attachment
Homework Equations
The Attempt at a Solution
Second Attachment.
- I have only attempted part (i) so far, because I am not sure if I am doing it correctly. I was thinking since the value of the latent heat of pentane is given, surely it has to be...
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 =...
Hi, I'm doing a lab at home on photosynthesis for biology, in which I have to boil leaves in ethanol, and I have a few questions about safety for this. First of all, is it at all safe to actually boil denatured alcohol/ethanol, especially where people might inhale it? And depending on how safe...
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 have tested this with 3 thermometers, 2 Taylor digitals and a candy thermometer...
My water boils at 96 celcius and I'm in Pattaya Thailand with sea elevation of 8 meters...
Actually slow boil at 93-94 and very heavy boil at 97-97
I'm perplexed...!
While boiling water, I was thinking: Would one liter of water boil faster or slower if I boil it all at the same time, or if I do it in stages, ie: First boil one deciliter, then add a deciliter and wait it to boil, and so on until there's one liter of boiling water.
Stated a bit more...
I was trying to compare some solubilities (in water) and some boiling points, and I could not explain it for some molucules. Also, I have some doubts in the theory itself.
Why is 2-pentanone more soluble than pentanoic acid?
Why is a ketone more soluble than the respective aldeyde...
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 is more efficient to bring water to a boil?
1. Using the low setting on heat
2. Going full blast to get it to boil as fast as possible
For a vehicle, developing velocity is more economical with slow accelaration, but would it be the same with boiling water?
Does it take less BTU...
After hours of reading and googling, I still do not really understand how boiling works.
I have some questions:
What I know is that boiling occurs when the vapor pressure is equal to the atmospheric pressure. But I thought that vapor pressure is the pressure exerted by the water vapor...
Hi guys,
I'm designing a simple waste heat recovery Fire Tube Boiler. The Flue gas inside the tubes has an average temperature of 300 C (572 F).
The tubes are submerged in water at a pressure of 6 atm, this gives us the saturated steam temperature of 158.83 C ( 318 F).
I've calculated The...