mindmap flashcards
what member of the em spectrum is used in nmr spectroscopy
radio waves
what is a pharmacaphore
the section of medicine that creates an effect
what is a chromophore
the section of a molecule that produces a colour in the compound - found where there is a conjugated system
what is the hybridisation of alkanes
sp3
what is the hybridisation of alkenes
sp2
what is the hybridisation of alkynes
sp
what is the hybridisation of benzene
sp2
what do we call the two types of nucleophilic substitution
Sn1 and Sn2
which mechanism do primary haloalkanes react with
sn2
which mechanism do tertiary haloalkanes react with
sn1
which mechanism do secondary haloalkanes react with
sn2
what is the intermediate in an sn2 mechanism
a transition state
what is the intermediate in an sn1 mechanism
a carbocation, where the group has been removed and leaves the carbon with a positive charge
what is a dative covalent bond
a covalent bond where the shared pair of electrons both came from one species in the bond
what is a ligand
something that binds to a central ion
what is a homogenous catalyst
a catalyst that is in the same state as the reactants
what is a heterogenous catalyst
a catalyst that is in a different state to the reactants
what is meant by ligand field splitting
the binding of the ligand causes a shift in the energy of the d orbitals. the orbitals become no longer degenerate and electrons can be promoted into the split orbital
why are many transition metal complexes coloured
absorption of energy to move electrons to the higher d orbital is in the visible range so transition metals show the colour on the opposite of the colour wheel
explain the role of d orbitals in catalysis
unpaired or unfilled d orbitals can allow intermediate states to form in the catalytic pathway
what is an indicator
a substance with a clear colour change caused by distinct colours on each side of an equlibirium
outline the steps for producing a calibration curve in colourimetry
- a range of samples are prepared of known concentration
- colorimeter readings are taken with the wavelength that is most appropriate - ie has the greatest absorbance
- dilutions to get samples are generally linear, but can be serial to give range.
why is heating under reflux used
prevents volatile reactants or products escaping while heating
why is distillation used
can be used to assess purity by looking at the point at which a substance is separated by distillation
what is the purpose of recrystallisation
to purify an impure solid
describe the steps involved in recrystallisation of an organic compound
- dissolving an impure solid gently in a minimum volume of hot solvent
- hot filtration of the resulting mixture to remove any insoluble impurities
- cooling the filtrate slowly to allow crystals of the pure compound to form, leaving insoluble impurities dissolved in the solvent
- filtering, washing and drying the pure crystals
if the partition coefficient is high, which layer is the solute most soluble in
upper solvent
describe the process of solvent extraction
- the solvent used must be immiscible with the liquid mixture or solution
- the solvent must also be one which the solute is more soluble in than the liquid mixture or solution, volatile enough to allow the solute to be obtained by evaporation of the solvent, and unreactive with the solute
- extracting with multiple small volumes of solvent will extract a greater volume of solvent than a single extraction
