Lab Midterm Flashcards
Why do we need to wash inorganic with h20?
Inorganic products are soluble in water
Why do we need to wash it with acetone?
Organic products are insoluble in water but soluble in acetone
What is the function of ground-glass joints?
These joints allow the various pieces of glassware to fit together snugly when connected
These ground-glass joints allow a wide variety of apparatus to assemble from a few pieces of glassware
What is the problems of ground-glass joints? How to solve?
They tend to freeze or stick together. Solving: applying a thin film of silicone grease to the inner member of the joint before connecting the two pieces.
What is the function of boiling chips?
Boiling chips are frequently employed in distillation and heating. When a liquid becomes superheated, a particle of dust or a stirring rod can cause violent flash boiling. Boiling chips provide nucleation sites so the liquid boils smoothly without becoming superheated or bumping.
Prevent bumping.
What is heating under reflux?
Heat a solution for long time without losing any of solvent to evaporation
What does reflux involve?
Involves heating a solution to boiling and then returning the condensed vapors to the original flask before they are lost by evaporation.
Why does water enter from bottom to the top at the condenser?
It is a water-cooled condenser for solvents with low boiling points
What is the functions of recrystallization?
Used to purify solids, which designs to remove the impurities and bring the reaction product to a pure state.
What is melting point range?
A narrow melting range is a characteristic physical property that can be useful for identification.
A pure compound has a sharp melting point
An impurities has 2 effects on melting point:
- Lower or depress the melting temp.
- Board the meLting range.
What is distillation?
Used to pure a liquid mixture based on boiling points
How does recrystallization purify a compound?
During recrystallization, an impure solid compound is dissolved in a hot liquid until the solution is saturated, and then the liquid is allowed to cool. The compound should then form relatively pure crystals.
Why does the thermometer can’t touch into a boiling liquid?
Temp of liquid is higher than the true boiling point,
What is extraction?
Is the physical process by a compound is transferred from one phase into another.
What is the functions of IR ?
To determine the functional group
How to describe the IR
Shape can be broad or sharp
Intensity can be weak/ medium/ strong
What is board?
OH, NH = has H bonding
C=0 very polar
These bonds tend to board.
What is sharp?
Nonpolar
C=C
C three bonds C
