What is Boiling: Definition and 319 Discussions

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.

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  1. M

    Thermodynamics (entropy) of boiling a liquid

    Hi I would like to consider the thermodynamics of boiling a liquid to a gas. I am assuming there are no intermolecular forces in a gas. I am also presuming intermolecular forces in a liquid are exothermic, though people hardly ever talk about the energy of IMF Lets assume the the...
  2. H

    Electric kettle that shuts off when boiling

    Electric kettle that shuts off when boiling... How does it do it?! I bought one this weekend and I think it is really cool...but I wonder how it does it. My guess is that it has some pressure sensor that detects the difference when the water is boiling...but I really wonder about the...
  3. T

    What are the effects of boiling in a heat exchanger?

    I'm working on a heat exchanger design, with water as the coolant. I'm running an analysis on this thing, and it looks like it's going to get hot. Like, 900F hot. So, of course this is going to be steam by the time it reaches the outlet. I'm really not a fluids kind of girl, but it's on me to...
  4. S

    What is the Boiling Point of Mineral Oil in a Vacuum?

    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...
  5. S

    Boiling Point of Nitrogen References

    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...
  6. A

    Explaining the Science Behind Boiling Water with Ice | Homework Solution

    Homework Statement I need to explain what happened here... My teacher boiled water in a flask using a bunsen burner. Then he stoppered the flask and turned it upside down and boiled the water using ice. Homework Equations • Boyle’s Law is the principle that at a constant...
  7. B

    Ice and Boiling Water Experiment: Discover the Surprising Results

    "Ice In Boiling Water?" If you nearly fill a test tube with cool water and then take a piece of ice and press it down on the bottom of the tube with a small weight, heat the test time with a flame that licks only the upper part of the tube, the water will start to boil sooner or later.But the...
  8. A

    Boiling point of water in a closed container

    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...
  9. A

    Boiling Point H20 @ 600 psi?

    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...
  10. D

    Specific Heat Capacity of a cylinder in boiling water

    Homework Statement Finding the specific heat capacity of an unknown metal. A cylinder was placed into boiling water, originally at 24.2 C. The heat transferred from the metal, and the water then was 29.5 C. Original Temperature-24.2 C Temperature after the metal has been placed into the...
  11. C

    Question on the Boiling point of NaCl solution.

    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...
  12. J

    Boiling an egg at high altitude

    Homework Statement an egg boiled for 4 minutes at the top of a mountain does not harden Homework Equations The Attempt at a Solution pressure is lower at the top of a mountain than at sea level. Is the issue here the fact that pressure inside the egg does not build up sufficiently to...
  13. A

    Vapor pressure, its decrease and subsequent lowering of boiling point

    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...
  14. S

    Understanding Boiling Point: Factors That Affect Liquid Vapor Pressure

    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...
  15. B

    Can Small Amounts of Chemicals Lower Water's Boiling Point?

    Is there any catalyst or substance that can do this?
  16. C

    Specific Heat Problem and boiling water

    Homework Statement 140 grams of boiling water (temperature 100° C, heat capacity 4.2 J/gram/K) are poured into an aluminum pan whose mass is 1100 grams and initial temperature 24° C (the heat capacity of aluminum is 0.9 J/gram/K). After a short time, what is the temperature of the water...
  17. C

    Gas that turn into liquid have a boiling point?

    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...
  18. P

    Boiling Point & Van der Waals Force: Weight Dependency

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

    Pressure due to boiling a liquid

    I am looking for an equation to determine the pressure produced by boiling a liquid. (On the net I can only find information on the effect that pressure has on boiling point) for example, the pressure produced by heating liquid nitrogen to 0K. Any help would be great! Thank you
  20. L

    Chemistry Boiling Points and Intermolecular Forces

    I am given question with a number of compounds such as He, Ne, Cl2, (CH3)2CO, O2, O3 I have to arrange it in increasing/decreasing order of their boiling points. It is related to intermolecular forces i.e London forces, dipole-dipole interactions and also deals with the concepts of...
  21. S

    London Forces, current, and boiling and melting points

    Alright, so I've posted this in physics forum not so long ago, but still haven't gotten any responses. Ok, so we know that the more electrons there are in the valence shell of an atom, the stronger the London Dispersion Forces are, and therefore, the compound will have a higher melting and...
  22. W

    Finding normal boiling point given pressure and enthelpy.

    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...
  23. J

    How is boiling different from evaporation?

    Thinking about this, I would say that there really is no difference. When water evaporates, surface molecules gain enough kinetic energy to change state (if it even makes sense to talk about state in the thermodynamic sense when dealing with discrete molecules). During boiling, you are giving...
  24. N

    Strange water boiling phenomenon

    Since I'm around that old question about an observed phenomenon came to my mind: - a cup is filled with water and heated up using a microwave oven. When I see it starting to boil, the oven is stopped abruptly. And while there is no more energy injected into the water, it boils even more for a...
  25. Q

    Boiling 2 Eggs: How Long Will It Take?

    If it takes 10 min to hard boil 1 egg, how long will it take to boil 2?
  26. S

    How does molecular shape affect boiling point in organic compounds?

    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...
  27. T

    Predict Boiling Points of Molecules: CH_{3}F, C_{2}H_{6}, CH_{3}OH, C_{2}H_{4}

    Homework Statement For the following molecules, predict the order of their boiling points from highest to lowest. 1. CH_{3}F 2. C_{2}H_{6} 3. CH_{3}OH 4. C_{2}H_{4} The Attempt at a Solution I think the answer is 3 4 2 1. I put 3 first because it is an alcohol and has hydrogen...
  28. S

    Question on normal boiling point and enthelpy of vaporization

    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...
  29. D

    Calculating Boiling Point of HF: ΔH and ΔS Equation Analysis

    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...
  30. S

    Raising boiling point of salt water

    How much salt per quart does it take to raise the temperature of water to 325 degrees at 28 PSI? I am sorry to say I am not educated in physics but I do understand the more particles in the water the higher the boiling point. I am trying to plasticize animal horns in a pressure cooker with a...
  31. I

    Comparing Boiling Points of Methanal & Ethanal

    Why is there a difference in boiling points between methanal (CH2O) which is -21degrees Celsius and ethanal (CH3CHO) which is +21degrees Celsius?
  32. fluidistic

    Calculating the boiling point of water

    Hi, I'm looking through wikipedia for a formula to calculate the boiling point of liquids in function of the atmospheric pressure but I didn't find any. In fact I'm curious what it would be for water on the Moon, Jupiter and so on. By the way, is the fusion point pressure-dependent? I...
  33. O

    Where Can I Find a Comprehensive Boiling Points Table for Various Substances?

    Hi, I opened a thread here yesterday and it was deleted, I don't know why, I hope I'm in the right forum. I'm looking for a table of substances and their boiling points. The closest thing I found was: http://chem.sis.nlm.nih.gov/chemidplus/" but for all of the substances I searched it...
  34. N

    Incorrect Thermometer Readings: What's the Boiling Point?

    1. A thermometer is calibrated wrongly. At the melting point, it reads -10 degree celsius. At 50 degree celsius, it reads 60 degree celsius. What does the thermometer read at the boiling point? 2. I think this is logic-based. 3. I drew a table but got confused.
  35. D

    Calculating Heat Transfer from Boiling Water on Skin

    Homework Statement If 4.0 g of boiling water at 100.0°C was splashed onto a burn victim’s skin, and if it cooled to 45.0°C on the 37.0°C skin, (a) how much heat is given up by the water? (b) How much tissue mass, originally at 37.0°C, was involved in cooling the water? Homework Equations...
  36. L

    Cruel thread: how long could one survive in a pot of boiling water?

    I just watched a cooking show on tv which showed how they always boil lobsters till death. We people have done some sadistic things in the past. Being cooked to death was one of them. How long could one survive?? I'm thinking you'd die pretty fast because water is such a fast conductor...
  37. F

    Figuring out a stove top temperature using boiling water

    hey everyone, how funny it is that i have a real life problem that fits nicely into a physics problem. I am going to start roasting my own coffee on my stove top. I need 350 constant heat. The problem is that my stove top just has a dial, and no temperatures (and i, conveniently, have no...
  38. T

    Why is steam hotter than boiling water?

    I know I should get this, but I don't... So, I've been told that whenever I put some water into a kettle and then heat it to the boiling point, the steam coming from the kettle is hotter than the boiling water. Why is that? And why is the temperature graph usually depicted as it is at...
  39. M

    What is the boiling point of water

    Homework Statement In Breckenridge, Colorado, the typical atmospheric pressure is 520. torr. What is the boiling point of water (ΔH = 40.7 kJ/mol) in Breckenridge? What pressure would have to applied to steam at 331°C to condense the steam to liquid water? Homework Equations Not...
  40. C

    Derivation of boiling an egg formula using laplace transformation

    I have been set a challenge to derive the formula for boiling a “perfect” soft-boiled egg, (essentially a thermal diffusion equation), in terms of the mass of the egg, the specific heat capacity and thermal conductivity of an egg, the initial temperature of the egg and the temperature of the...
  41. P

    Boiling point on top of mount everest

    Homework Statement At what temperature does water boil on the top of mount everest, elevation z = 8848m? Recall that the dependence of pressure with altitude is give by: P=P_atm * exp(-MWgz/RT) MW=molecular weight of the gas, P_atm =atmospheric pressure, g is the gravitational...
  42. T

    Sort these substances by boiling point

    HCOOH C_4H_10 C_2H_6 CH_2 H_2they all are polar covalent except H_2 which is pure covalent how to sort them??
  43. K

    Will heating a closed tank of water cause bubbles to form?

    If I heat up a tank with water while it is completely closed, will the water then form bubbles while it heats up above 100 °C? I know the pressure will increase so I think the bubbles won't form, but I'm not sure. But for the pressure to increase we need gas, so I would say that the gas...
  44. D

    Cooking Veggies: Boiling or Steaming - Which is Faster?

    Explain! Please * You can cook es by vegatables by dropping them into boiling water or by placing them in a basket over boiling water, putting the lid on the potand steaming them. Which method do you think would be faster? Explain your reasoning.
  45. K

    Searching for DME + H2O Boiling Point Curve: Help Needed

    I've been searching for a DME + H2O boiling point composition curve. Can someone help me here or give me a clue how to calculate the curve?
  46. P

    What Happens to dU, dQ, and dW During Boiling?

    Boiling Internal Energy - URGENT A quick question: dU = dQ - dW What are dU, dQ and dW during Boiling? I thought: -the particles do work, hence dW is + -dU increases as particles gain more energy so dQ = dU + dW - showing that heat flows in. Which made sense to me. Or is...
  47. R

    Melting and boiling temperatures of different substances

    Hi all I am sorry for the double post, I just found out there is a homework help place here.. I have this question in a practice physics exam: The table lists melting and boiling temperatures of 4 different substances, A,B,C,D.. The question is "Which substance is a gas at 25 C?"...
  48. E

    Vapour Pressure| Boiling| Atmospheric P

    Ok I do not get WHY an object boils when atmospheric pressure is equal to Vapour pressure. Can anyone explain this? In my textbook it doesent explain it at all.
  49. W

    Boiling water - amount of steam

    Hello! There is an observation I have made when boiling water - amount of steam getting out of the kettle increases when the heating is turned off. Could anyone help to explain that? The experiment goes like this. Take a kettle, start heating the water. The amount of the steam getting out...
  50. E

    How Does Boiling Water Affect Energy Calculations?

    Homework Statement A kettle containing 1kg of boiling water is heated until complete evaporation. Calculate q, w, "delta"U and "delta"H for this process. Suppose that the water vapor is an ideal gas and molar "delta"H of vaporisation at 373K = 40.6kJ/mol.Homework Equations H = U + PV "delta"U =...
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