Colligative Properties
Name: JOANNA CELESTE M. QUINTANA Date performed: NOV. 12, 2012
Section: C-1L Date submitted: NOV. 21, 2012
Group Number: 3
Exercise No. 2
COLLIGATIVE PROPERTIES
(Full Report)
I. INTRODUCTION
Colligative properties
In liquid solutions, particles are close together and the solute molecules or ions disrupt intermolecular forces between the solvent molecules, causing changes in those properties of the solvent that depend in intermolecular attraction. For example, the freezing point of a solution is lower than that of the of the pure solvent and the boiling point is higher. Colligative properties of solution are those that depend on the concentration of solute particles in the solution, regardless of what kinds of particles are present the greater the concentration of any solute, the lower the freezing point and the higher the boiling point of a solution.
FREEZING POINT LOWERING
A liquid begins to freeze when temperature is lowered to the substance’s freezing point and the first few molecules cluster together into a crystal lattice to form a tiny quantity of solid. As long as both solid and liquid phases are present at the freezing point, the rate of crystallization equals the rate of melting and there is a dynamic equilibrium. When a solution freezes, a few molecules of solvent cluster together to form pure solid solvent and a dynamic equilibrium is set up between the solution and the solid solvent.
In the case of a solution, the molecules in the liquid in contact with the solid solvent are not all solvent molecule. The rate at which molecules move from solution to solid is therefore smaller that in the pure liquid to achieve dynamic equilibrium there must be a corresponding smaller rate of escape of molecules from solid crystal lattice. This slower rate occurs at a lower temperature and so the freezing point of the solution is lower than that of liquid solvent. The change in freezing point ∆Tf is
Section: C-1L Date submitted: NOV. 21, 2012
Group Number: 3
Exercise No. 2
COLLIGATIVE PROPERTIES
(Full Report)
I. INTRODUCTION
Colligative properties
In liquid solutions, particles are close together and the solute molecules or ions disrupt intermolecular forces between the solvent molecules, causing changes in those properties of the solvent that depend in intermolecular attraction. For example, the freezing point of a solution is lower than that of the of the pure solvent and the boiling point is higher. Colligative properties of solution are those that depend on the concentration of solute particles in the solution, regardless of what kinds of particles are present the greater the concentration of any solute, the lower the freezing point and the higher the boiling point of a solution.
FREEZING POINT LOWERING
A liquid begins to freeze when temperature is lowered to the substance’s freezing point and the first few molecules cluster together into a crystal lattice to form a tiny quantity of solid. As long as both solid and liquid phases are present at the freezing point, the rate of crystallization equals the rate of melting and there is a dynamic equilibrium. When a solution freezes, a few molecules of solvent cluster together to form pure solid solvent and a dynamic equilibrium is set up between the solution and the solid solvent.
In the case of a solution, the molecules in the liquid in contact with the solid solvent are not all solvent molecule. The rate at which molecules move from solution to solid is therefore smaller that in the pure liquid to achieve dynamic equilibrium there must be a corresponding smaller rate of escape of molecules from solid crystal lattice. This slower rate occurs at a lower temperature and so the freezing point of the solution is lower than that of liquid solvent. The change in freezing point ∆Tf is
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