Why does steam burn more than boiling water?
403230
It takes quite a lot of energy for water to change phase.  Steam actually contains much more energy than does boiling water, therefore it burns far worse when it comes in contact with human skin.\n\nSee the link below.  You can actually do the math to confirm this -- it takes 100 cal/gm to heat water from 0 to 100 degrees C, but 539 cal/gm to change that water into steam.  So ten grams of water at 0 degrees C absorbs 1000 calories to boil but nearly 6400 calories to turn completely into steam.\n\nThat's a lot of heat.\n\nIn rebuttal to some of the other answers, burns are caused (I believe) by heat convection -- that is, the hot substance in direct contact with the skin, transferring its heat to the skin cells and damaging or destroying them.  Water is more likely to stay in contact with the skin than steam is, because steam is a gas that rises away from the skin.  This is why some people seem to erroneously believe that steam doesn't burn.\n\nHowever if skin comes into continuous contact with steam, it will burn, and quite badly.
412906
To turn liquid water into steam the weak bonds between the molecules have to be broken and the molecules accelerated enough to leave the water surface and become vapour. This requires energy supplied by heating. \n\nNow add salt.\n\nThe salt consists of NaCl crystals. In water these dissolve into Na+ and Cl- ions. These ions will become surrounded by water molecules that are attracted to them, forming large clumps of molecules. To break these bonds requires more energy than in the case where the salt was absent.\n\nWe have to supply this extra energy and the result is boiling at a higher temperature.
336893
You've used 258.3kJ to boil the water.\n\nIf you use 2400 kJ/kg to turn water to steam, and you waste 50g of water then;\n\n=> 2400 / 1000 * 50 = 120 kJ\n\nTotal Energy used = 258.3 + 120 = 378.3 kJ
413190
Here is the best answer...\nhttp://science.howstuffworks.com/steam1.htm
700465
its the same concept when comparing a cup of 100 degree coffee to a hot tub filled with 100 degree water.  the hot tub is hotter because even though the temperature is the same the total heat and energy in the hot tub is greater.  remember that heat measures the total energy of the substance and temperature is just the average kinetic energy.  since there is more substance in then hot tub there will be more heat.
706671
At a higher altitude, water boils at a lower temperature, because the boiling point of a liquid is the temperature at which the liquid's vapor pressure equals that of the atmosphere.  At high altitudes, the atmospheric pressure is lower than at sea level.\n\nSo it doesn't actually boil "faster", it reaches each temperature at the same rate on a mountain as at the seashore.  It's just that the temperature needed to boil it on the mountain is lower.
383320
the idea isn't that water can't heat up when it boils at low pressure, but that it doesn't have to. no matter what temperature something is, its molecules are moving somewhat, and some of them escape as a gas. also, any gas always is condensing into a liquid or solid. when pressure and tempurature are constant, these processes reach equilibrium where they cancel each other out. at high temperature, more gasses escape, and at low pressure, less gases return to liquid. so at somewhat low temperature and relativly lower pressure, even though few gases relatively escape, even fewer return to liquid, so the net effect is that the liquid evaporates at low temperature. if the temperature were raised, it would boil even faster.
1165215
Yes, this is called latent heat. The best example of this, is if you are boiling water at atmospheric pressure at sea level. If you placed a thermometer in this steadily heating water the temp would rise in a fairly uniform manner to about 96 degrees celsius, where upon it would seem to get stuck. The reason being, the heat energy is being used up to change the state of matter of the liquid water to steam. Until this transition is complete there will be no change in sensible heat as measured at the thermometer. Jules, lecturer. Australia.
514471
There is a difference between boiling and evaporating.\nAt 100 degrees water starts boiling. The temperature can not rise because al the energy you put in is used by the molecules to 'escape' and the water to change into gas. That is why damping water cools off. But water kan evaporate also at lower temperatures because molecules can 'escape'. The molecules are not as volatile as at 100 degrees, but they are volatile. Winds helps because the dryer the air, the easier it is to escape. Is the air humid, than the molecules can be caught in the water again. \nSorry I am not a chemist but I think this is it essentially.
195177
It  isn't boiling.\n\nIt steams because it is well above the temperature of the surrounding air.\n\nWhen the air heated by the hot water in the teacup rises, and reaches the cooler room of the air, the moisture condenses.\n\nBoiling is 212 F. Room temperature might be 70 F.
766842
1. microwaves heat water faster than boiling it over a heat source.\n\n2. microwaves have a more direct effect on an atom, since the energy is transferred directly form the MW to the atom, unlike the boiling water where it is transferred from heat source to water to the thing (w/ enzymes). the longer path means longer time.\n\n3. since the atoms (or molecules for enzymes) directly interact with the MWs, they are more likely to be destroyed than when boiling water is used. Hence the shorter time to ensure deactivation, and not destruction, is achieved
734492
Heat = mass x specific heat of material x change of temperature.\nSpecific heat of water is 1. So the amount of heat needed to be added is the mass of the water x the amount of change needed to get to boiling. So cold water does not boil faster. \n\nsalt will cause it to take longer. \n\nPeople think that tea tastes betterr if you start with cold water, which holds more oxygen. As you heat the water, the oxygen comes out. This may look like boiling.
651919
From the website below:  \n\nDesign Fault In The RBMK Reactor - The RBMK reactor type used at Chernobyl suffers from instability at low power and thus may experience a rapid , uncontrollable power increase. Although other reactor types have this problem they incorporate design features to stop instability from occurring. The cause of this instability is: \n\n  > Water is a better coolant than steam \n\n  > The water acts as a moderator and neutron absorber (slowing down the reaction) whilst steam does not. \n\nExcess steam pockets in the RBMK design lead to increased power generation - this is known as a positive void coefficient. This excess power causes additional heating thus producing more steam and means less neutron absorption causing the problem to escalate. This all happens very rapidly and if it is not stopped quickly it is very hard to stop as it supplies itself.
128890
technically, when water reaches boiling point, the temperature doesn't rise further. although water can make the ingredients of the soup soggy, too much heat can make the water evaporate faster leaving a soup soup-less, so i guess that makes it a fair advice
115995
You <can> measure steam. It is merely water in a gaseous state; gases occupy volume just like liquids.\n\nI'm not totally sure what you're asking though. Do you mean that during the boiling process, 1tsp (0.005L) of liquid water generates 2 gallons (7.5708L) of water vapour? \n\nThat's a pretty massive expansion, but if it is the case, the ratio of liquid:steam would be\n0.005:7.5708\nor\n0.001:1.51416\nor \n1:1514.16
450246
If you're going to boil your potatoes in rapidly boiling water, be sure to use enough water so it doesn't evaporate out of the pan and scorch your potatoes.  The reason for using vigorously boiling water in cooking pasta is to keep it moving in the pan so it doesn't stick to itself and come out in one big ugly glob of starch.  To shorten your potato cooking time, cut them in to pieces, and let them gently boil.
372176
Sounds like you've got too much time on your hands to me!  The ions in solution keep the water molecules farther apart from eachother on average than they would be in pure water.  Therefore the hydrogen bonds are weaker and the water will boil at a lower energy level.  At least that's what I'd guess.