Elevation will change the melting and boiling points. Exothermic deicers, which release heat to melt the ice, work the quickest and are effective at a broader range of temperatures. Like all chloride-based materials, rock salt is moderately corrosive to unprotected common metals. Ice is the solid form that liquid water takes when it is cooled below 0 degrees Celsius (32 degrees Fahrenheit). While salt will melt snow and ice down to a pavement temperature of -6 degrees F, it can melt over five times as much ice at 30 degrees F as at 20 degrees F. Thus the effectiveness of salt is sensitive to small differences in pavement temperature. Room temperature is approximately 25 degrees Celsius. Melting converts solid ice to a liquid, and upon further heating, the liquid evaporates to form water vapor. At elevations higher than 2000ft, the equilibrium state changes because of decreased air pressure. So, ice begins to melt when the temperature rises above 0 degrees Celsius. It must draw heat from the surroundings to form an ice-melting brine. The common answer is 32 F or 0C. Source. At 30 0 F, 1 pound of salt will melt about 46 pounds of ice. Ice melts due to the chemical properties of water. Impurities alter the temperature … The lowest melting point of the water and ice-melt compound solution is termed the “eutectic” temperature. Ice melts at temperatures above 0 degrees Celsius. The problem, however, is that those two products are calcium chloride (CaCl2) salt and are the most dangerous of all the products on the list. Road salt works by lowering the freezing point of water via a process called freezing point depression. "Sodium chloride melts ice at temperatures down to its eutectic point of –6° F (-21° C). The important variable is not the air temperature in this case, but the pavement temperature. When ice melts, it absorbs as much energy as it would take to heat an equivalent mass of water by 80 °C. At or below 32°, it will remain frozen. Ice forms when the­ temperature of water reaches 32 degrees Fahrenheit (0 degrees Celsius), and that includes ice on roadways. "Sodium chloride melts ice at temperatures down to its eutectic point of –6° F (-21° C). Therefore, ice will melt in a glass at room temperature. Salt will “work,” i.e. Objects melt when they have reached an appropriate temperature and pressure where they can transition from their solid phase to their liquid phase. Like all chloride-based materials, rock salt is moderately corrosive to unprotected common metals. Three factors that affect the rate at which ice melts are temperature, pressure, and the presence of impurities. Once the ice is melted, the temperature of the water will warm until it reaches the temperature of the room Facilitator's Note: Contrary to our instincts, the melt water's temperature will not increase as long as ice is present. The Celsius temperature scale was established using the melting point of water as 0° and the boiling point of water as 100°. Ice cubes melt as the molecules of air, water or other substances around the ice transfer heat into the molecules of the ice itself. Commercially available ice melt materials include salt (sodium chloride), calcium chloride, and magnesium chloride. In the highway deicing world the practical working temperature of salt is generally considered to be above 15 0 F or even 20 0 F. There are two reasons for this. At a temperature of 30 degrees (F), one pound of salt (sodium chloride) will melt 46 pounds of ice. At temperatures above 32°F (0°C), pure water ice melts and changes state from a solid to a liquid (water); 32°F (0°C) is the melting point. As an example, rock salt ice melt products will lose their effectiveness once the temperature outside goes lower than 20°F. Lawns and other plants can be harmed if rock salt deicer is over-applied or large quantities are directly applied to grass or vegetation. The important variable is not the air temperature in this case, but the pavement temperature. Depending on the type of ice melt product you’re using, the effectiveness of melting ice on sidewalks, driveways, roads, and highways will change based on the overall temperature. As you can see, only Driveway Heat and Excel 50 melt ice at a colder temperature than Safe Paw. With a lowest effective temperature of +20°F (-7°C), rock salt is a relatively slow and ineffective ice melter when temperatures are coldest. What are the conditions for melting, crystallization, evaporation and condensation of water? Sodium chloride does a good job at melting ice when temperatures are above 16 degrees Fahrenheit (minus 9 Celsius), according to the video. At 20 0 F, 1 pound of salt will only melt about 9 pounds of ice. One is that the amount of ice that can be melted per pound of salt (or any other deicer) decreases with temperature. For example, solid calcium chloride releases heat and is effective down to –25 degrees Fahrenheit. Other ice melting products such as magnesium chloride (that's what I use at home) remain effective even with bitterly cold temperatures. As the temperature increases, the bonds change inside the ice, entering a liquid phase and turning into water, according to About.com.