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A comprehensive set of questions and answers covering various topics in chemistry, including intermolecular forces, recrystallization, tlc, and sn1/sn2 reactions. it's a valuable resource for students preparing for exams, offering detailed explanations and examples to aid understanding of key concepts. The questions are designed to test comprehension and application of theoretical knowledge.
Typology: Exams
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How do you know an acid is contaminated from the bottle?
contaminated acids are not clear
What are the two things to do if you get an acid or base on your skin
immwsiately flush the area of your skin with water for 10 min and tell your TA.
Why is acetone a usefull solvent?
it dissolves many compounds with low water solubility
What does each household object stand for in lab 1 (eggs, sugar, aluminum foil, and styrofoam)
Prior to begining an experiment what should be in your lab notebook?
Before you leave the classroom it is important to remove what?
Gloves
Extensive properties
dependent on the amount of sample used
Intensive properties
tips for a good recrystallization
refractive index
n= (velocity of light in air)/(velocity of light in liquid)
Mixed melting point
10% of a known compound is added to an unknown sample. If the melting point of the unknown solid by itself matches the mixed melting point, there is strong support that the unknown solid and the known solid are the same.
Strongest to weakest intermolecular forces
hydrogen bonding, dipole-dipole interactions, London dispersion forces
oiling out
a condition where the solid melts in the recrystallization solvent but does not dissolve.
percent weight recovery
(mass of recrystallized compound)/(mass of impure compound) x 100
What does TLC test for?
What is stationary phase and what are the most common layers?
Retention Factor
a ratio used to characterize and compare components of samples in liquid chromatography
(distance compound travels)-A/(distance solvent travels)-B
When looking at a TLC plate how do you know that it is polar or non polar
The solvents most polar do not move much up the TLC plate, but non polar ones move all the way up.
When showing hydrogen bonding and silica TLC plate where must the bonds go towards
The bonds goes towards the acceptors lone pair
Lewis acids and bases do what to electrons?
lewis acid: accepts
lewis base: donates
Bronsted acids and bases do what to protons?
acid: donates
base: accepts
When pka increases, what happens to the acidity?
The higher the pka the weaker the acid and the lower the pH
Organic acids only react with what?
Organic bases only react with what?
When two solids mix together they are seperated into what layers?
constitutional isomers
same molecular formula, different connectivity
reflux
What is the source of Bromine?
During the reflux, why do you place the reaction flask in water and not sand.
Nucleophiles
electrophiles
leaving groups
good LGs:
bad LGs:
ugly LGs:
SN2 reaction
-bimolecular nucleophilic substitution reactions
-nucleophile attacks the compound at the same time as the leaving group leaves
product determination
beilstein test
What is a thin colorless layer that is formed on top of a reaction mixture?
Would you expect 1-butanol or 1-bromobutane to have a lower boiling point? Describe the intermolecular forces present in each to justify your answer and indicate which of these forces are stronger
SN1 reaction
how do leaving groups affect sn
how does carbocation stability and alkyl halide structure affect sn1?
Before you leave the classroom it is important to remove what?
Gloves
How do you know an acid is contaminated from the bottle?
contaminated acids are not clear
What are the two things to do if you get an acid or base on your skin
immwsiately flush the area of your skin with water for 10 min and tell your TA.
Why is acetone a usefull solvent?
it dissolves many compounds with low water solubility
What does each household object stand for in lab 1 (eggs, sugar, aluminum foil, and styrofoam)
Extensive properties
dependent on the amount of sample used
Intensive properties
The _____ the intermolecular forces, the ____ the energy to overcome them and the ____ the boiling and melting point
n= (velocity of light in air)/(velocity of light in liquid)
Mixed melting point
10% of a known compound is added to an unknown sample. If the melting point of the unknown solid by itself matches the mixed melting point, there is strong support that the unknown solid and the known solid are the same.
Strongest to weakest intermolecular forces
hydrogen bonding, dipole-dipole interactions, London dispersion forces
oiling out
a condition where the solid melts in the recrystallization solvent but does not dissolve.
percent weight recovery
(mass of recrystallized compound)/(mass of impure compound) x 100
What does TLC test for?
What is stationary phase and what are the most common layers?
What interactions can silica gel take place in?
What is a mobile phase?
Liquid that moves past the surface of the silica gel
What type of compounds move up a TLC plate rapidly?