melting and boiling point purpose?
152501
You really should write a more detailed question.  But I think you're asking "why do things melt and boil?"\nA solid will convert into a liquid when the Intermolecular forces are over come by the raising average Kinetic engery(Temperature) and then it boils when those forces are over come enough to break away and become a gas.
742562
The melting point is the same as the freezing point, usually. The freezing/melting point is usually lowered to a lower temperature by impurities due to the impurities "messing up" the crystal lattice of the solid phase. The crystal lattice cannot form as easily with a lot of garbage present, so it requires a lower temperature to accomplish freezing. Likewise, the polluted crystal lattice will melt easier and thus it will melt at a lower temperature. This is why we put anti-freeze into our car radiators, to keep your engine block from cracking from the freezing of the coolant water during freezing weather. I hope this helps
730844
OK...You can start with the equation of DG (I'm using D instead of writing "delta").\n\nDG = DH -TDS  You've seen that equation, right?  OK..Since the boiling point of water is 100 degreed C at 1 atm pressure, we are really talking about an equilibrium situation.  So, DG= 0.\n\nConsequently, DH = TDS.  \n\nSince you know DH and you know T (in Kelvin), you can calculate DS.  Make sure that you convert DH into Joules (instead of kilojoules) before you finish the problem.
639379
The boiling point elevation constant of water is required\n\nThe formula is T = Kfm where m is molality and T is rise in temp.
109177
i believe its because the boiling point of water is only 212 at normal atmospheric pressure, so if the pressure is changed the boiling point does too.
670047
Melting point 933.47 K\n(660.32 °C, 1220.58 °F)\n\nBoiling point 2792 K\n(2519 °C, 4566 °F)
929239
because hot water has more energy than cold, giving the molecules more energy to move(melt)faster\n\n (i am trying to get to level 2 best answerer would help)
229195
When you add a salt to water and the container feels cold, yes, an endothermic reaction is taking place.  The solution is grabbing heat from the surroundings to get the salt to dissolve.  When you add a salt to a pure solvent (say, water), the freezing point will go down and the boiling point will go up.  That's because the vapor pressure of the pure solvent is lowered (this would be easier to explain with a phase diagram).  Remember, the definition of BP is the temp at which the solution's vapor pressure equals the external pressure.  By lowering the vapor pressure, the whole phase diagram shifts...BP to the right (higher), FP to the left (lower).  You may want to check out a intro level chemistry text or at least draw out the phase diagram to see more clearly what gets lost is just words here.  Did you ever try boiling water without heating it?  If you have the means, hook up a vacuum to a flask of water.  You don't change the vapor pressure of the water, but you reduce the external pressure enough so that the water does boil.\n\nOne more thing...  The change in BP and FP is related to how much salt is added to the solvent:  delta T (change in T) = Km  where K is either what's called the molal freezing-point depression constant or molal boiling-point elevation constant;  m is the molality of the solution defined as moles of solute (salt) / kilograms of solvent. By knowing the constant for the solvent, how much solvent you have and how much solute you add, you can predict by how much (in degrees (C) the BP or FP will change.\n\nI would just like to add a couple of more comments... The reaction that is endothermic in this case is  NaCl(s) --> Na+(aq) + Cl-(aq)  ...  The reason that the freezing point is lowered is as J. Schultz said - the vapor pressure is lowered ....  However there is a simple analogy (that may be useful) which gives a simplified picture ... Freezing involves the water molecules becoming very ordered in crystalline lattice...  However when there are foreign particles such as Na+ and Cl- ions in the water they hinder the formation of the crystalline structure because they interfere with the intermolecular forces between the water molecules.  Also, the freezing point depression and boiling point elevation are called colligative properties...  that is, they are properties that depend only on the number of solute particles and not on their chemical properties...  The third famous colligative property is osmotic pressure.
977052
You need a variable in any experiment to compare results. Perhaps you could use cold (ice) water in one container, warm in another and hot or boiling in another. You can then make your prediction on which will dissolve first and have an experiment that will verify whether you have made an accurate prediction.
123942
The normal boiling point is, of course 100 degrees Celcius at standard pressure at sea level (760 torr). \n\nHowever, boiling point depends on several factors:\n\n1. What is the pressure? At higher altitudes, water boils at lower temperatures.\n\n2. Is it pure water, or water containing dissolved materials and other impurities? For example, dissolved salt can raise the boiling temperature by a few degrees.  \n\n3. Water can be superheated, in a microwave, and be above its normal boiling point without boiling. People have been scalded by this.
530330
Ice melting\nWater freezing\nWater boiling\nAmmonium chloride subliming
758944
The melting point of a crystalline solid is the temperature at which it changes state from solid to liquid. When considered as the temperature of the reverse change from liquid to solid, it is referred to as the freezing point.\n\nFor most substances, melting and freezing points are equal. For example, the melting point and freezing point of the element mercury is 234.32 kelvins (−38.83 °C or −37.89 °F). However, certain substances possess differing solid-liquid transition temperatures. For example, agar melts at 85 °C (185 °F) and solidifies from 32 °C to 40 °C (89.6 °F to 104 °F); this process is known as hysteresis. Certain materials, such as glass, may harden without crystallizing; these are called amorphous solids.\n\nThe melting point of water at 1 atmosphere of pressure is 0 °C (32 °F, 273.15 K), this is also known as the ice point. In the presence of nucleating substances the freezing point of water is the same as the melting point, but in the absence of nucleators water can supercool to −42 °C (−43.6 °F, 231 K) before freezing.\n\nUnlike the boiling point, the melting point is relatively insensitive to pressure. Melting points are often used to characterise organic compounds and to ascertain the purity. The melting point of a pure substance is always higher than the melting point of that substance when a small amount of an impurity is present. The more impurity is present, the lower the melting point. Eventually, a minimum melting point will be reached. The mixing ratio that results in the lowest possible melting point is known as the eutectic point.\n\nThe chemical element with the highest melting point is tungsten, at 3695 K (3422 °C, 6192 °F). The often-cited carbon does not melt at ambient pressure but sublimates at about 4000 K; a liquid phase only exists above pressures of 10 MPa and estimated 4300–4700 K. Tantalum hafnium carbide (Ta4HfC5) is a refractory compound with a very high melting point of 4488 K (4215 °C, 7619 °F).[1] At the other end of the scale, helium does not freeze at all at normal pressure, even at temperatures infinitesimally close to absolute zero; pressures over 20 times normal atmospheric pressure are necessary.\n\n\n--------\n\n\nThe boiling point of a substance is the temperature at which it can change its state from a liquid to a gas throughout the bulk of the liquid at a given pressure. A liquid may change to a gas at temperatures below the boiling point through the process of evaporation. Any change of state from a liquid to a gas at boiling point is considered vaporization. However, evaporation is a surface phenomenon, in which only molecules located near the gas/liquid surface could evaporate. Boiling on the other hand is a bulk process, so at the boiling point molecules anywhere in the liquid may be vaporized, resulting in the formation of vapor bubbles.\n\nA somewhat clearer (and perhaps more useful) definition of boiling point is "the temperature at which the vapor pressure of the liquid equals the pressure of the surroundings."\n\nThe reaction\n\nSomething that should not emembered is that boiling is evidenced by the appearance of bubbles containing vapor from the liquid. [Note: The bubbles that precede real boiling in the pot on the stove are either (formerly) dissolved gas or water vapor forming on the very hot bottom of the pot that will be condensed before it can get to the top of the liquid.] Production of vapor requires energy and thus does not occur without some source of energy. This source can be a hot surface or even the liquid itself. Hot liquid will boil as it rises through the bulk liquid if the pressure of the environment drops to the vapor pressure of the liquid at its temperature. This production of vapor will not quickly stop because the temperature of the liquid will not be reduced by the vaporization thus reducing the vapor pressure.\n\nSaturation temperature and pressure\n\nA saturated liquid or saturated vapor contains as mu
87453
Distillation... if the liquids have boiling points within 100 degrees celsius, then fractional distillation should be used.  Otherwise, simple distillation is a lot easier.
658781
Freezing and Boiling points of Water are:\n\n 0 and 100 degrees Celsius\n32 and 212 degrees Fahrenheit\n\nFrom the equation of a straight line,\n\nF = mC + A\n\nwhere m is the gradient and A is a constant\n\nm = (212-32)/(100-0) = 1.8\n\nF = 1.8C + A\n\nwhen x=0, F=32\n\n32 = 1.8(0) + A\n\nA = 32\n\nTherefore the final equation is:\n\nF = 1.8C + 32\n\nor\n\nC = (F - 32)/1.8
358448
specific heat? that would be represented by Cp.\nHowever if you are using delta H then it would either be: delta H (fus) which is the enthalpy of fusion, used in problems concerning melting point (indicating a state change from solid to liquid)\nOr it could be delta H (vap) which is the enthalpy of vaporization, used in problems concerning a boiling point (indicating a state change from liquid to gas)\n\nHeat calculations are done using the formulas:\nq=m x (delta T) Cp <-- Used when there is a temperature change, but no state change\ng= m x (delta H fus) <-- Used for state changes from solid to liquid\nq= m x (delta h vap) <-- Used for state changes from liquid to gas
399313
A bi-metallic strip is used to convert a temperature change into mechanical displacement. The strip consists of two strips of different metals which expand at different rates as they are heated, usually steel and copper.\n\nThe copper melting point is (1084.62 °C, 1984.32 °F)\nSteel often melts at around 1370 degrees C (2500°F).\n\nIt doesn't have a freezing point because it's a solid.
676099
Heat the substance and once u see steam, wa lah u got a boiling point... don't forgot the thermometer.