EXAM 1 (EXP 2, 3, 6, 8) Flashcards
What are some distinct types of information that can be found in a compound’s material safety data sheet (MSDS)?
- chemical identification (name and CAS
number) - Hazardous ingredients, if a mixture of
chemicals - Physical data (such as bp or mp)
- Flammability and explosion danger
- Reactivity data
- Health hazards (toxicity)
- First aid and emergency information
- Measures to control exposure (PPE)
- Spill handling procedures
- Special procedures, waste disposal
What WWU document contains information pertaining to emergency procedures,
storage and handling of hazardous materials, proper disposal of hazardous materials (waste),
laboratory clothing policy, and methods of training workers?
Chemical Hygiene Plan
Which will travel fastest in TLC- a polar or non-polar compound?
non-polar compound will travel up fastest
Which will elute first in column chromatography - a polar or non-polar compound?
most non-polar compound will elute first
Will your Rf values change if you replace the TLC solvent with pure acetone instead of DCM?
Rf values will be larger, but the order would stay the same as if you were using DCM as a solvent
Why do you determine the response factor for each component in GC?
Because the detector does not detect the components equally
What is an azeotrope?
A mixture of liquids which are unable to be separated by distillation
While performing column chromatography, a colored band shows excessive tailing as it passes through the column. How can you fix this problem?
Increase the polarity of the solvent constantly while eluting
What does TLC stand for?
Thin-Layer Chromatography
What are 2 scenarios where good separation can be achieved by only simple distillation
- the BP differences are large (over 100 degrees C)
- less than 10% of impurity is present in the mixture
Put the IMFs in order of strongest to weakest: Hydrogen Bonding, electrostatic attraction, van der Waals, Dipole-Dipole, Ion-Dipole
Electrostatic > Ion-dipole > Hydrogen Bonding > Dipole-Dipole > van der Waals
Explain how Chromatography separates molecules
separates molecules based on how strongly they absorb to the solid phase or how quickly it absorbs in liquid (based on polarity and IMFs)
What does the Rf value tell you?
How quickly a compound moves in reference to other compounds in the mixture
How do you determine if your compound is pure in TLC?
There will be only one spot
What can TLC tell you?
compound composition/purity as well as the progress of a reaction
What is the elutant (or eluate) in column chromatography?
The solutes or materials to be separated
What is the eluent in column chromatography?
the solvent
Explain how you can correct the following TLC:
a 2 compound mixture gave only one spot with an Rf=0.95. Solvent was acetone
Decrease the polarity of the solvent
Explain how you can correct the following TLC:
a 2 compound mixture gave only one spot with an Rf=0.05
Increase the polarity of the solvent
Explain how you can correct the following Column Chromatography:
the substances you are trying to purify stop moving down the column
Increase the polarity of the solvent
How do you choose a good solvent for crystallization?
High solubility at high temps and low solubility at low temps
What happens if your solvent’s boiling point is higher than the melting point of the solid?
“oil out” - the solid melts before it dissolves
What should you do if you get a precipitate during the crystallization cooling process?
Reheat and add more solvent, start again!
Can you ever get 100% recovery from crystallization?
Why? (2 reasons)
No- there is always impurity present in the starting compound which will cause a loss of some mass as you remove the impurity.
Some of your compound will always remain dissolved in the solvent.
When do you use the semi-microscale method for crystallization?
When the weight of the solid to be crystallized is more than 0.1 g
When do you use the microscale method for crystallization?
When the weight of the solid to be crystallized is less than 0.1 g
What is “mother liquor”?
the solution that remains after a crystallization
name this piece of equipment:
Conical Vial
name this piece of equipment:
Craig Tube
name this piece of equipment:
multipurpose adapter
name this piece of equipment:
Centrifuge Tube
name this piece of equipment:
Erlenmeyer Flask
name this piece of equipment:
Spin Bar
name this piece of equipment:
Spin Vane
name this piece of equipment:
Thin-walled vial
name this piece of equipment:
Claisen head adapter
name this piece of equipment:
Water-cooled reflux condenser
name this piece of equipment:
distillation head
name this piece of equipment:
Vacuum take-off adapter
name this piece of equipment:
Round-Bottom Flask
name this piece of equipment:
thermometer adapter
name this piece of equipment:
Air reflux condenser
name this piece of equipment:
Hirsch funnel
name this piece of equipment:
Filter Flask
name this piece of equipment:
Separatory Funnel
name this piece of equipment:
Büchner Funnel
How do you calculate weight (g)?
density (g/mL) x volume (mL)
What does the retention time tell you from GC data?
How long the component satyed in the GC column
higher BP = higher retention time
What does the peak area tell you from GC data?
Used to determine the relative amount of different components
