Chap 5: The Separation and Identification of the Components of Mixtures Flashcards
What is a solution?
A solution is a homogenous mixture of two or more different substances, where one is dissolved in another.
What is an aqueous solution?
When water is used to dissolve a solid, liquid or gaseous substance.
Particles dissociate and can more freely.
What is the solute?
The chemical substance that is dissolved in the solution
What is the solvent?
The substance in which the solute dissolves.
In aqueous solutions, water is always the solvent.
What does it mean for a solution to be homogenous?
The solute and solvent must be mixed together and cannot be differentiated from each other.
eg. sea water –> salt + water
What are the three different kinds of intermolecular forces that need to be considered?
- Intermolecular forces between solvent particles
- Intermolecular forces between solute particles
- Intermolecular forces between solute and solvent particles
How can a substance dissolve?
“Like dissolves like,”
The intermolecular forces between solute particles and between solvent particles need to be overcome by the intermolecular forces between the solute and solvent
Why are most molecular substances insoluble in water?
The solute-solvent forces between water and these molecules cannot overcome the stronger hydrogen bonding present between the water molecules and dipole-dipole forces between solute molecules.
Why are there a select few molecules that will dissolve in water?
- molecules form hydrogen bonds with water molecules
- the molecules ionise in water
What is chromatography?
It is an analysis technique used to separate the components of a mixture.
What is the process of chromatography?
The solvent, known as the mobile phase, is passed through a mixture over a medium known as the stationary phase.
They then go through a continual process of adsorption to and desorption from the stationary phase
What do the results of chromatography tell us?
The polarity of the mobile phase and of the stationary phase dictates how strongly each component adheres to the stationary phase and how readily each component desorbs by redissolving in the mobile phase
What is adsorption?
Adsorption is a mass transfer process that is a phenomenon of sorption of gases or solutes by solid or liquid surfaces
What is the principle of seperation?
Some substances will be more strongly attracted than others
How do you find the retention front?
distance travelled by the sample/ distance travelled by the solvent
