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. S

    Cracking of hydrocarbons and boiling point of salt water

    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...
  2. T

    Understanding the Boiling Point: Thermodynamic Proof

    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...
  3. djh101

    Boiling toluene/water azeotrope mixture?

    Can somebody explain what happened in this experiment? The mixture of toluene/water was heated to its boiling point (without a condenser) of about 84C. Over the course of under a few minutes, the boiling point increased rapidly and then remained constant at about 96C (more or less- it jumped up...
  4. D

    Phase Change and Lowest Boiling Point

    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...
  5. M

    Enthelpy of vapourisation vs boiling point

    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?!
  6. S

    Effects of soluble impurities boiling and melting points

    In my textbook, it says that impurities lower the melting point and increase the boiling point. But is this only true if the boiling point of the impurity is greater than the boiling point of the solvent, and the melting point is greater than of the solvent too? So essentially, if greater...
  7. A

    Freezing and Boiling water at the same time

    Hi, As I understand, by placing water in a vacuum and decreasing pressure, vapor pressure will subsequently be increased causing the water to boil. The water will then evaporate, which will cool the water that is left behind. Further evaporation over a period of time will drop the water...
  8. M

    Can Hot Beverages Stay Hot at High Altitudes?

    Can you explain why we can have hot beverages at really high altitude don't stay hot? Why can't they have a nice pot of tea on mount everest?
  9. S

    Boiling and melting point of impure substances

    They say that an impure substance has an increased boiling point and reduced melting point (i know that they will melt/boil at a range of temperature). But does impurity mean that its melting and boiling point is higher than the substance itself or it doesn't matter? I think that the impurity...
  10. M

    Determing Boiling Point elevations in lab

    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?
  11. JJBladester

    Boiling above and below supercritical pressure

    Homework Statement How does the boiling process at supercritical pressure differ from the boiling process at subcritical pressure? Homework Equations N/A The Attempt at a Solution I know that the critical point is the point on a P-v diagram where the saturated liquid and saturated vapor...
  12. T

    Vapor pressure and the boiling point of a liquid

    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...
  13. P

    Calculating Molal Boiling point elevation constant HELP

    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...
  14. L

    1 kg of melting ice and 1 kg of boiling water are mixed

    1. 1 kg of melting ice and 1 kg of boiling water are mixed: Which temperature will have the mixture when all ice is liquefied ? I don't know if there is formula The attempt solution: I don't know this question is really hard there are not enough information
  15. L

    Rate of heat transfer passing from the boiling water to the ice bath

    Homework Statement A copper rod of length 0.20 m and cross-sectional area 6.00 10-2 cm2 is connected to an iron rod with the same cross section and length 0.28 m (the figure below). One end of the copper is immersed in boiling water and the other end is at the junction with the iron. If the...
  16. I_am_learning

    Can Temperature Sensing Prevent Milk from Boiling Over?

    I don't know about you people, but I often loose my milk, because it boils and spills out, just when I am not looking at it. :) Is it possible to alarm when it is just about to boil, by sensing its temperature? My concern is, is temperature a reliable indicator (impurities, varying degree of...
  17. K

    Best vac pump for boiling water

    Hello all, I am seeking advice on the best, relatively cheap vacuum pump to pump water vapor from the 2 kPa range to the 100 kPa range. Essentially any pump that would work well at boiling water at room temperature would work for me. I'm hoping that someone on here may have done that as a...
  18. T

    Boiling Water via New Solar Panel Method

    For a science project, I plan to come up with a reliable way to produce clean water from the sun. I've toyed with ideas of using fresnel lenses and parabolic concentrators, but none of them solved all the problems I had. Then, I thought of using multiple—and when I say multiple I mean about...
  19. P

    Find True Boiling Point with Barometric Pressure

    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.
  20. Y

    Impurities on melting point and boiling point of water

    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...
  21. S

    Boiling point and vapor pressure

    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...
  22. S

    Boiling point and vapor pressure

    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...
  23. jaumzaum

    Why acetaldehyde has a higher boiling point than ethylamine?

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

    Calculate Normal Boiling Point of Ethyl Alcohol

    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...
  25. R

    Is the boiling point directly related to the volatility of a substance?

    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?
  26. S

    Blackbody Radiation of Boiling Water

    I was thinking about this the other day and I wanted some other input on the matter. Cups of boiling water (I was thinking about coffee) give off gobs of IR radiation at both near and mid wavelengths. Could I think of a coffee mug as an approximate black body for IR radiation? The insulation of...
  27. T

    Effect of Pressure on Heating (not boiling) water

    I understand that if I apply pressure to water in a closed system, the boiling point increases. So at atmospheric pressure, it boils at 100 degrees C and at 100 PSI, this number increases to 164 degrees C. In my experiment, I'm using the sun to heat the water as it runs through a solar water...
  28. T

    Which substance has the highest boiling point?

    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??
  29. S

    0 Celsius for ais , 100 Celsius for boiling water ?

    0 Celsius for ais , 100 Celsius for boiling water ? As we know that is common for study. But anyone know where is origin ? What i mean is ...is it valid at every country ?
  30. P

    Investigating Specific Heat Capacity with Boiling & Warm Water

    I am doing a lab about specific heat. i have a cup of boiling water which i put 5 metals into, and a cup of warm water which sits at 22 degrees celcius. i am to record the difference in temperature as i am using the equation Q = mc (delta) T for part one, and then i am using the equation C = Q/m...
  31. P

    What is so magical about the melting and boiling points?

    Melting and boiling explanation based on the kinetic-molecular model have always confused me. I am in grade 12 and still don't feel that I have got any real understanding of the process. Something that has always seemed odd to me is that the idea of increase in potential energy is only mentioned...
  32. J

    How to Calculate Heat Required to Boil Water?

    Water is boiled to add moisture to the air in the winter to help a congested person breathe better. Calculate the heat required to boil away .75 L of water that is initially 60 C. I'm not sure what equation to use, I was thinking Q=mc(change in temp.) where Q= heat energy m= mass...
  33. E

    Exploring Boiling Water vs. Pressurized Water Design Flaws

    Except that they are boiling water vs pressurized water. I am interested to know if there were design flaws.
  34. H

    Predicting missing boiling point in the following series of compounds:

    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...
  35. A

    Caculating normal boiling point using an equation of a line

    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...
  36. P

    Can a vacuum of 1.5 Bar be used to lower the boiling point of liquid?

    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...
  37. Simfish

    Using boiling temperature as a proxy for vapor pressure

    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...
  38. C

    What happen to the kinetic and potential energy during the boiling and melting?

    I know this question is probably chicken feet to most of the people here, and I hope I am posting on the right thread. But I am just curious about 2 questions; 1 - Where does the kinetic and potential energy comes from in a substance? 2 - How are the kinetic and potential energy affected by...
  39. Z

    Boiling Point before Melting Point?

    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...
  40. B

    Physical state of water at 80 degrees C on the upswing or downswing of boiling.

    I have read that many tea masters insist that when infusing a tea that requires less-than-boiling water, you should first let the water reach a full 100 degrees C and let it cool back down to the target temperature, rather than take it off the burner as it is approaching boiling. I think it was...
  41. T

    Among the six measurements of the boiling point of a silsicon compound

    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...
  42. H

    Boiling Points and Melting Points

    In Atoms in the Family: My Life with Enrico Fermi, Laura Fermi explains some of the games they played when they were in college. The following is an excerpt from the book which I need help understanding. "As you know, the boiling point of olive oil is higher than the melting point of tin. How...
  43. T

    Among six measurement of the boiling point of a silicon compound,

    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...
  44. A

    Specific Volume of Boiling Liquid

    Why the specific volume of a liquid decreases with the increase in pressure at saturation temperature and why the specific volumes of vapor at saturation temperature decreases with increasing pressure??
  45. O

    Comparing Boiling Points of Two Pairs of Materials

    I have two materials that I have to decide who has a higher boiling point C2H5OH-CH3OH this is the First duo here i have no idea how to know. and i have The second pair:CH3CH2CH2CH2OH-CH3OCH2CH2CH3 is will be correct if i will say that CH3CH2CH2CH2OH have the higher boiling point then...
  46. P

    Disagreements in published boiling temperatures of tin, gallium etc.

    I have noted big disagreements of a scale of hundreds of degrees centigrade in published values for the boiling temperature of chemical elements such as tin and gallium. For example, Tin http://en.wikipedia.org/wiki/Tin" - 2602 °C, 2875 K, ...
  47. L

    What does vigorously boiling water do?

    IF I am cooking something like potatoes, vigorously boiling water won't reduce my cooking time. What does it do then?
  48. P

    Estimate the boiling temperature of HCN at 1 bar.

    Homework Statement The standard molar enthalpy of vaporization for HCN is Δ_vap H = 26.23 kJ mol^−1 vap Estimate the boiling temperature of HCN at 1 bar without using tabulated thermodynamic data. Provide your answer in units of ºC . Homework Equations I figure Trouton's rule would...
  49. K

    Boiling point at a certain pressure

    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...
  50. I

    Time to reduce volume of water by boiling?

    Mayhaps anyone provide assistance in determining how long it would take to reduce a specific volume of water (well, a solution, mostly water) to a smaller volume by boiling it? i.e. boil 15 gallons down to 5 gallons? Rule of thumb I've used is 5% of volume per hour, but I know it varies...
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