Chris and Mike
In our experiment we determined the boiling points of solutions to verify that solutions boil at higher temperatures than water. We boiled Gatorade, orange juice and water over a Bunsen burner and measured their boiling points. The averages of the results were that: Gatorade boils at 103.7oC, orange juice boils at 102.24oC, and water boils at 100.4oC. We concluded that solutions, (Gatorade and o.j.), boil at higher temperatures than pure solvents, (water), because of two colligative properties of solutions: boiling point elevation and vapor pressure lowering.
The boiling point is the temperature at which the vapor pressure of the liquid exceeds the pressure of the atmosphere above the liquid. Solutions have higher boiling points because of colligative properties. Colligative properties are properties of solutions which depend only on the number of particles present, without regard to type. One property, boiling point elevation, means that the boiling point is raised due to the amount of solute particles dissolved in a solution. Nonvolatile solute particles in a solution raise the boiling point because a higher temperature is needed to put the solvent particles into vapor phase. The second colligative property, vapor pressure lowering, states that nonvolatile solutions have higher boiling points than pure solvents because they have lower vapor pressures. According to Raoults Law, the addition of solute to water lowers the percentage of water molecules in the total solution, decreasing the tendency for the molecules to escape as a gas. Since Gatorade and orange juice consist of solute particles added to water, they start out with lower vapor pressures than water so it takes more heat to raise the vapor pressures to the point at which they exceed the surrounding pressure.