Chemistry
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Chemistry
to determine average h-bonds a molecule can make, find which is
less (lone pairs or h bonded to polar molecule)
- multiple the total number of the less species by 2
P(total) = ∆moles( P(reactants) - P(products) ) + P(products)
When Case 3 Imitates Case 1
- K2 >> K1 ; K-1 =0
When Case 3 Imitates Case 2
- K1 >> K2 ; K-1 >> K2
In enzymatic catalysis:
- [S]0 >> [E]0 (true for most enzymatic reaction, and results in [S] >>
[E dot S ], and [S]0=[S]
- catalysts can be included in rate law
1/time vs ln[A] will produce linear graph in first order reactions
- diluting the starting solution (weak acid) with water will not change
the ph at 1/2 EQ point
- diluting the starting solution (weak acid) with water will change ph at
the equivalence point because ph depends on initial concentration of
weak acid
(Based on Q 27 of 2014)
IMFs:
- In pure substances:
- LDFs
- D-D forces
- H bonds
- In solution
- ion-ion (i.e. hydrated ions)
- ion-dipole (i.e. hydrated ions)
- DO not have a significant effect on gases, as molecules are well
separated.
LDFs:
- induced-dipole - induced-dipole forces
- non-polar molecule
- experiences an instantaneous dipole
- which induces a dipole in its neighbour
- instantaneous dipole propagates throughout the sample
- strength depends on polarizability (tendency for the charge
separation to occur)
- force strength increases with:
- atomic number and size of molecule
- linear vs branched structures (linear is stronger because they
can 'stack' on top of each other.
D-D forces:
- occur in polar molecules (w/ permanent dipoles)
- have bond dipoles and asymmetrical shape
H-bonding:
- b/w an H atom in a polar bond (H-N, H-O, H-F)
Ionic interactions:
- very favourable in solids
- weaker in solution
- unfavourable in water
Supercritical fluids:
- their viscosity is b/w that of corresponding gas and liquid
- have low surface tension (approaches 0)
- its density is greater than that of the gas and less than that of the
liquid
- density of liquid and gas are equal
- supercritical drying avoids structural collapse of fragile materials by
avoiding large capillary forces
Conventional drying:
- involves liquid-gas phase boundaries that exert huge capillary forces
on samples - collapsing them
Freeze-drying:
- solid-gas boundary which can still collapse fragile structures
Supercritical drying:
- avoids any phase boundaries
- used to dry biological samples
- do not collapse fragile structures
Application for SC fluids:
- alternative to dry cleaning solvent tetrachloroethylene
- solvent for organic chemistry (drug synthesis)
- caffeine extraction from coffee (decaffeination)
Phase diagrams
- negative slope between solid and liquid means that solid is less
dense than the liquid
Orgo:
Boat conformation:
- 6 equatorial substituents
- 6 axial substituents ( 4 below plane, 2 above plane)
Chair conformation:
- 6 equatorial subsitutents
- 6 axial substituents (
to determine average h-bonds a molecule can make, find which is
less (lone pairs or h bonded to polar molecule)
- multiple the total number of the less species by 2
P(total) = ∆moles( P(reactants) - P(products) ) + P(products)
When Case 3 Imitates Case 1
- K2 >> K1 ; K-1 =0
When Case 3 Imitates Case 2
- K1 >> K2 ; K-1 >> K2
In enzymatic catalysis:
- [S]0 >> [E]0 (true for most enzymatic reaction, and results in [S] >>
[E dot S ], and [S]0=[S]
- catalysts can be included in rate law
1/time vs ln[A] will produce linear graph in first order reactions
- diluting the starting solution (weak acid) with water will not change
the ph at 1/2 EQ point
- diluting the starting solution (weak acid) with water will change ph at
the equivalence point because ph depends on initial concentration of
weak acid
(Based on Q 27 of 2014)
IMFs:
- In pure substances:
- LDFs
- D-D forces
- H bonds
- In solution
- ion-ion (i.e. hydrated ions)
- ion-dipole (i.e. hydrated ions)
- DO not have a significant effect on gases, as molecules are well
separated.
LDFs:
- induced-dipole - induced-dipole forces
- non-polar molecule
- experiences an instantaneous dipole
- which induces a dipole in its neighbour
- instantaneous dipole propagates throughout the sample
- strength depends on polarizability (tendency for the charge
separation to occur)
- force strength increases with:
- atomic number and size of molecule
- linear vs branched structures (linear is stronger because they
can 'stack' on top of each other.
D-D forces:
- occur in polar molecules (w/ permanent dipoles)
- have bond dipoles and asymmetrical shape
H-bonding:
- b/w an H atom in a polar bond (H-N, H-O, H-F)
Ionic interactions:
- very favourable in solids
- weaker in solution
- unfavourable in water
Supercritical fluids:
- their viscosity is b/w that of corresponding gas and liquid
- have low surface tension (approaches 0)
- its density is greater than that of the gas and less than that of the
liquid
- density of liquid and gas are equal
- supercritical drying avoids structural collapse of fragile materials by
avoiding large capillary forces
Conventional drying:
- involves liquid-gas phase boundaries that exert huge capillary forces
on samples - collapsing them
Freeze-drying:
- solid-gas boundary which can still collapse fragile structures
Supercritical drying:
- avoids any phase boundaries
- used to dry biological samples
- do not collapse fragile structures
Application for SC fluids:
- alternative to dry cleaning solvent tetrachloroethylene
- solvent for organic chemistry (drug synthesis)
- caffeine extraction from coffee (decaffeination)
Phase diagrams
- negative slope between solid and liquid means that solid is less
dense than the liquid
Orgo:
Boat conformation:
- 6 equatorial substituents
- 6 axial substituents ( 4 below plane, 2 above plane)
Chair conformation:
- 6 equatorial subsitutents
- 6 axial substituents (
