Chem. Lab. Flashcards
It is the process of separating components of a mixture.
Chromatography
Several types of Chromatography:
- Elution or column;
- Paper;
- Thin layer;
- Gas chromatography.
These are the two phases in Chromatography:
- Stationary phase
- Mobile phase
The phase in which the mobile phase passes, like the special filter-type of paper.
Stationary phase
It is a phase that passes in and around the stationary phase and is characterized as solvent or a mixture of solvents.
Mobile phase
It refers to the mixture of organic compounds applied as a spot on the paper to be distributed between the two phases.
Solute
It refers to the liquid where the paper is placed in that moves more rapidly than the solute.
Solvent
It refers to the ratio of the rate of movement of the solute to the rate of movement of the developing solvent. The ratio can be expressed in terms of the distances moved by each.
RF value (rate of flow)
It is a form of matter that refers to combinations of two or more elements and/or compounds. Thus, it has no constant composition.
Mixture
It is a form of matter that has a constant and definite composition and properties.
Substance
This compound contains the element carbon and hydrogen.
Organic compound
This compound has no eitheir carbon nor hydrogen.
Inorganic compound
It refers to the temperature at which the solids melts or turns into a liquid state.
Melting point
It is defined as the temperature at which the liquid and solid phases are in equilibrium.
Melting point of a solid
It is known as the melting point range of a solid.
0.5 - 1.0°C
It generally melts sharply because the forces of attraction between its particles are the same.
Pure solid
It melts at lower temperature and over a wider ranger.
Impure solid
It is defined as the temperature range over which a small amount of solid in a thin walled capillary tube first visibly softens (first drop of liquid) and then completely liquefies.
Capillary melting point
Solid’s melting point is useful not only as an aid in identification but also as an indication of ____?
Purity
It refers to the temperature at which the vapor pressure of the liquid exactly equals the pressure exerted on it, causing the liquid to “boil” or change to the gas phase.
Boiling point
The close proximity of molecules in the liquid state allow these molecules to interact via _____?
Non-covalent interactions (dipole-dipole, H-bonding, van der Waals forces)
True or False
No covalent bonds are broken during a change from the liquid phase to the gas phase.
True
True or false
If lack of energy (often in the form of heat) is provided to the liquid, the molecules begin to move away from each other by “breaking” the non-covalent forces that hold the compound in the liquid state.
False - If enough energy
These are two processes through which matter changes from one state to another.
- Evaporation
- Condensation
