What effect does adding compounds like salt have on the temperature of water when it boils?The sooner that this question can be answered the better. This week I'm writing my introduction for my...

What effect does adding compounds like salt have on the temperature of water when it boils?

The sooner that this question can be answered the better. This week I'm writing my introduction for my science fair project, and I need this question for my project.

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ncchemist | eNotes Employee

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Adding dissolved solids to a liquid solvent like water will increase the liquid range of the solution.  This means that the freezing point will be lowered and the boiling point will be raised.  So adding salt to water will make it boil slightly above 100 degrees C.  There is an equation for measuring the increase in the boiling point.  It is given below.

deltaT = k*i*b

deltaT is the increase in the boiling point.  k is a constant that is specific for each solvent (0.512 for water).  i is called the van't Hoff factor and is an integer equal to the number of different ions or particles dissolved in the water (i=2 for salt since it is composed of two ions Na+ and Cl-).  b is the molality of the solution which is measured as moles of solute per kg of solvent.

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