Boiling+Point+Elevation

Boiling-Point Elevation: When a solute is added to a solution, the boiling point ( the point at which atmosphereic pressure equals vapor pressure) of the solution increases. change in T=(i)(k)(m) where: i= the vant hoff factor, the number of particles into which the added solute dissociates k= the boiling point elevation constant for the solvent m= molality Created by Skyler Kuhn

**Factors That Affect the Boiling Point- contribution made by Molly Robinson **
The following graph shows the boiling point for water as a function of the external pressure. The line on the graph shows the normal boiling point for water. >  > > > > > > >
 * **//Pressure //**: when the external pressure is:
 * less than one atmosphere, the boiling point of the liquid is lower than its normal boiling point.
 * equal to one atmosphere, the boiling point of a liquid is called the **//normal boiling point //**.
 * greater than one atmosphere, the boiling point of the liquid is greater than its normal boiling point.
 * **//Types of Molecules //**: the types of molecules that make up a liquid determine its boiling point. If the intermolecular forces between molecules are:
 * relatively strong, the boiling point will be relatively high.
 * relatively weak, the boiling point will be relatively low.
 *  http://www.chem.purdue.edu/gchelp/liquids/boil.html

Hey its Rachael! Just wanted to add a few things... The change in boiling point of the solvent above a solution from that of the pure solvent is directly proportional to the molal concentration of the solute- **T = Kbm (**This is the same equation Skler wrote above, just writtin how you will most likely see it in class and on the AP exam)
 * [[image:http://www.chem.purdue.edu/gchelp/common/delta.gif width="15" height="15" align="bottom"]]T** is the change in boiling point of the solvent,
 * Kb** is the **molal boiling point elevation constant**, and
 * m** is the molal concentration of the solute in the solution.



The figures above illustrate how the vapor pressure of water is affected by the addition of the non-volatile solute, NaCl. The particles on the top half of the images represent water vapor, and the particles on the bottom half represent liquid water. The blue and green particles are the non-volatile solute, NaCl. Notice how there are more water vapor particles above the pure liquid water.

Here is a good visual representation about how boiling point and freezing point can be raised and lowered. [] Added by Drew Parcells

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