Salt changes the way that water behave when heated, and this change in the behavior of water are important for many people to understand. Salt increases the boiling point of water due to the fact that the salt particles makes it harder for the water molecules to escape the surface of the salt. Because it is more difficult for the water molecule to escape the surface of the salt water, more heat must being applied to the salt water before it reaches a boil.
The number of particles in the water is a factor in the boiling point of the water, but not the type of salt that are used. Due to the low concentration of salt in most kitchen, when salt is added to water for cooking activities like boiling pasta, the salt does not change the boiling point significant. Low concentrations of salt will raise the boiling point of salt water by a small amount only, and this slight change in boiling point will not change the amount of time it take to cook the pasta.
How Salt Affects the Boiling Point of Water
Instead, many cooks add salt to the boiling water to season the pasta. Many cooks add salt to the water to add flavor to the food, not to change the boiling point of the water. In addition to cooking pasta, salt may also be added to vegetable while boiling them in water.
Again, the boiling point of the water will not change to a noticeable extent. With higher concentrations of salt, however, there will be more noticeable change in the boiling point of water. For instance, if a brine is prepared as an part of a recipe for curing meat, the brine may contain a high concentration of salt, such as fifteen or twenty percent salt.
In these cases, several degree will raise the boiling point of the water. Furthermore, the salt will make the liquid denser. The density of the brine will cause the food to float in the brine, and the higher temperature will help to kill bacteria on the food that is submerged in the brine.
These high concentrations are much different than the salt concentrations use in most kitchens for cooking food. These concentrations of salt is represented on the upper end of the reference chart for boiling point. The same principle that explains how salt raises the boiling point of water also explains how salt lower the freezing point of water.
Salt makes it difficult for the water molecules in water to form the different state of that water, thus preventing the water from form steam or becoming ice. For these reasons, salt is often used in applications like road salt to prevent the roads from freezing during the winter month. Altitude can also affect the boiling point of water, but in a way that is different than the effect of salt on the boiling point of water.
At high altitude, air pressure is lower, meaning that it is easier for the water to reach its boiling point. Thus, when water is boiled at high altitudes, its boiling point will always be lower than boiling point of water at sea level. Even if salt is added to water at high altitudes, though, the boiling point will not rise to the same extent as the boiling point at sea level; salt cannot compensate for the lowered boiling point cause by altitude.
For these reasons, people who live at high altitudes use pressure cookers to increase the boiling point of the water for boiling foods. The type of salt will change the amount of salt that must be added to the water if measuring by volume, but the type of salt will not impact the boiling point of salt water if measuring by weight. For instance, table salt is very dense, so one teaspoon of table salt will contain more salt than one teaspoon of kosher salt.
Thus, when cooking, the salt should be measured by weight to ensure accuracy. Many types of salt contain other mineral besides sodium chloride. The other minerals in these types of salt has no effect on the boiling point of the water.
While it may be thought that salt increases the time for water to come to a boil, which is referred to as the boiling time, this belief is mostly incorrect. While salt does technically increase the boiling point of water, the rise in boiling point is too low to create a noticeable difference in the time for water to boil. The type of metal pot in which the water is boiling, the power of the burner heating the pot, and the initial temperature of the water actualy affect the boiling time more.
In addition to boiling water, salt is also sometimes added to water that is already boiling. Adding salt to boiling water, though, can cause the water to bubble and possibly even boil over from the added salt. By stirring salt into the water while it is heating, however, it is possible to avoid water boiling over when salt is added.
In general, salt changes the boiling point of water. At normal concentrations, though, the change in boiling point does not significant impact the cooking process. Therefore, salt is mostly used to flavor food, rather than to alter the boiling point of the water in which the food is cooked.
At high concentrations, though, salt significantly change the boiling point and density of water, which is essential knowledge for the creation of brines and other salty cooking application. Thus, understanding how each of these three factor impact the boiling point of water can help cooks to prepare food more effective.