ANSWERS: 7
  • When salt comes in contact with ice, it weakens the chemical bonds of the ice. This causes the ice to rapidly melt. http://antoine.frostburg.edu/chem/senese/101/solutions/faq/why-salt-melts-ice.shtml
  • decreases its freezing pt, causing it to melt.
  • If you live in an area with a cold and icy winter, you have probably experienced salt on sidewalks and roads, used to melt the ice and snow and keep it from refreezing. Salt is also used to make homemade ice cream. In both cases, the salt works by lowering the melting or freezing point of water. The effect is termed 'freezing point depression'. When you add salt to water, you introduce dissolved foreign particles into the water. The freezing point of water becomes lower as more particles are added until the point where the salt stops dissolving. For a solution of table salt (sodium chloride, NaCl) in water, this temperature is -21°C (-6°F) under controlled lab conditions. In the real world, on a real sidewalk, sodium chloride can melt ice only down to about -9°C (15°F). Freezing point depression is a colligative property of water. A colligative property is one which depends on the number of particles in a substance. All liquid solvents with dissolved particles (solutes) demonstrate colligative properties. Other colligative properties include boiling point elevation, vapor pressure lowering, and osmotic pressure. Sodium chloride isn't the only salt used for de-icing, nor is it necessarily the best choice. Sodium chloride dissolves into two types of particles: one sodium ion and one chloride ion per sodium chloride 'molecule'. A compound that yields more ions into a water solution would lower the freezing point of water more than salt. For example, calcium chloride dissolves into three ions (one of calcium and two of chloride) and lowers the freezing point of water more than sodium chloride. Here are some other de-icing compounds:
  • Salt is used to lower the freezing poit of water. When the pressure surrounding the liquid is increased, the freezing point is raised. The addition of some solids can lower the freezing point of a liquid, a principle used when salt is applied to melt ice on frozen surfaces. It helps to make the ice on roads melt a lower temps.
  • It dissolves into the film of water on top of the ice creating a salt water solution that has a lower freezing temperature than pure water. This has a compounding effect that creates more saltwater and continues melting the ice until the concentration of salt is too low to continue the process.
  • Lowers the freezing temperature causing it to melt.
  • After reading all that answers others have listed, the only thing I can add that no one else seems to have picked up on is: It makes salty ice water.... I hope my feeble effort amuses you....

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