Boiling point elevation is a colligative property that describes how the boiling point of a solvent increases when a solute is added. This phenomenon occurs due to the disruption of the solvent’s vapor pressure by the solute particles, requiring more heat to reach the boiling point. Here are three diverse, practical examples to illustrate this concept.
In the culinary world, adding salt to boiling water is a common practice when cooking pasta. This is not just for flavor; it also raises the boiling point of the water. When salt (sodium chloride) dissolves in water, it dissociates into sodium and chloride ions, which interfere with the water molecules’ ability to vaporize.
By adding about 58 grams of salt to 1 liter of water, the boiling point can increase by approximately 0.5 degrees Celsius. This means that instead of boiling at 100 degrees Celsius, the salted water may boil at around 100.5 degrees Celsius. The slight increase in boiling point might help cook the pasta more evenly, although the effect is minimal in practical terms.
In automotive applications, antifreeze (typically ethylene glycol or propylene glycol) is added to the water in car radiators. This solution not only lowers the freezing point but also raises the boiling point of the coolant.
For instance, a 50/50 mixture of water and ethylene glycol can raise the boiling point to about 107 degrees Celsius, compared to pure water boiling at 100 degrees Celsius. This elevation prevents the coolant from vaporizing at higher temperatures, ensuring efficient heat transfer and preventing engine overheating during operation.
In the study of oceanography, understanding the boiling point elevation of seawater is essential. Seawater has a salinity of about 3.5%, meaning it contains various salts, primarily sodium chloride. This salinity affects the physical properties of seawater, including its boiling point.
When seawater is heated, its boiling point increases due to the dissolved salts. For example, seawater with a salinity of 35 grams of salt per liter raises the boiling point to approximately 100.6 degrees Celsius. This elevation is significant for marine organisms that thrive in these environments, as they are adapted to the higher boiling point of their habitat.