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MCAT Org. Chem Ch.12
Term | Definition |
---|---|
Extraction: | Combines two immiscible liquids, one of which easily dissolves the compound of interest |
The Polar (Water) Layer Is Called: | The aqueous phase, and dissolves compounds with hydrogen bonding or polarity |
The Nonpolar Layer Is Called: | The organic phase, which dissolves nonpolar compounds |
Extraction Is Carried Out In: | A separatory funnel. One phase is collected, and the solvent is then evaporated |
Acid-base Properties Can Be Used To: | Increase solubility |
A Wash Is: | The reverse of extraction, in which a small amount of solute that dissolves impurities is run over the compound of interest |
Filtration: | Isolates a solid (residue) from a liquid (filtrate) |
Gravity Filtration Is: | Used when the product of interest is in the filtrate. Hot solvent is used to maintain solubility. |
Vacuum Filtration Is: | Used when the product of interest is the solid. A vacuum is connected to the flask to pull the solvent through more quickly. |
In Recrystallization: | The product is dissolved in a minimum amount of hot solvent. If the impurities are more soluble, the crystals will reform while the flask cools, excluding the impurities. |
Distillation: | Separates liquids according to differences in their boiling points; the liquid with the lowest boiling point vaporizes first and is collected as the distillate |
Simple Distillation: | Can be used if the boiling points are under 150C and are at least 25C apart |
Vacuum Distillation: | Should be used if the boiling points are over 150C to prevent degradation of the product |
Fractional Distillation: | Should be used if the boiling points are less than 25C apart because it allows more refined separation of liquids by boiling point |
All Forms Of Chromatography Use Two Phases: | To separate compounds based on physical or chemical properties |
The Stationary Phase Or Absorbent Is: | Usually a polar solid |
The Mobile Phase: | Runs through the stationary phase and is usually a liquid or gas. This elutes the sample through the stationary phase. |
Compounds With Higher Affinity For The Stationary Phase Have: | Larger retardation factors and take longer to pass through, if at all; compounds with higher affinity for the mobile phase elute through more quickly. |
The Process Of Compounds Getting Separated From Each Other During The Mobile Phase: | Partitioning |
Thin-layer And Paper Chromatography Are Used To: | Identify a sample |
The Stationary Phase Of Thin-layer And Paper Chromatography Is: | A polar material, either silica, alumina, or paper |
The Mobile Phase Of Thin-layer And Paper Chromatography: | Is a nonpolar solvent, which climbs the card through capillary action |
The Card Is Spotted And Developed: | Rf values can be calculated and compared to reference values |
Reverse-phase Chromatography Uses: | A nonpolar card with a polar solvent |
Column Chromatography Utilizes: | Polarity, size, or affinity to separate compounds based on their physical or chemical properties |
The Stationary Phase Of Column Chromatography Is: | A column containing silica or alumina beads |
The Mobile Phase Of Column Chromatography Is: | A nonpolar solvent, which travels through the column by gravity |
In Ion-exchange Chromatography: | The beads are coated with charged substances to bind compounds with opposite charge |
In Size-exclusion Chromatography: | The beads have small pores which trap smaller compounds and allow larger compounds to travel through faster |
In Affinity Chromatography: | The column is made to have high affinity for a compound by coating the beads with a receptor or antibody to the compound |
Gas Chromatography: | Separates vaporizable compounds according to how well they adhere to the adsorbent in the column |
The Stationary Phase Of Gas Chromatography: | Is a coil of crushed metal or a polymer |
The Mobile Phase Of Gas Chromatography Is: | A nonreactive gas |
High-Performance Liquid Chromatography (HPLC): | Is similar to column chromatography but uses sophisticated computer-mediated solvent and temperature gradients. |
HPLC Is USed If: | The sample size is small or if forces such as capillary action will affect results. It was formerly called high-pressure liquid chromatography. |