General concepts Flashcards
Resonance structures are separated in the stick diagrams by ______
double headed arrows
What are the two priniciples that decide which resonance structure is more stable?
one. atoms in general, “don’t like” charges, so having no charge is better.
two. The resonance structure with a complete octet is more stable.
which one is more stable?
the left side because the charge is on the bigger atom
which is more stable?
left side because the charge is on the bigger atom
what is this called - functional group
acyl halide
what is this called - functional group?
aldehyde
name this ___Butyl?
isobutyl
name this ___propyl
isopropyl
Name this?
propyl
name this red functional group
name this functional group in red
tert-butyl
name this
2,3 - dimethylpentane
Three steps of halogenation
Initiation, propagation and termination in Radical Halogenation.
What happens during the initiation
formation of radicals from a molecule by homolytic cleavage
What is the propagation step ?
Reaction between a neutral molecule and a radical.
What is the termination step?
Reaction of two radicals to form a molecule
what is this reaction?
Proton transfer
what do each of these arrows mean? With regards to electron transfer
The chair conformation of the cyclohexane is ___ more/less___ stable than the boat conformation?
more stable
note: a conformation having a lower energy implies higher relative stability
what are the two types of hydrogen-carbon bonds? in a cyclohexane
equatorial and axial
which is more stable?
the second conformation because of less steric interactions.
two types of catalysts?
heterogeneous and homogeneous
what does a catalyst do
- lower activation energy
- Provide an alternative route with a lower activation energy
- provide an alternative route with a lower activation energy
what is a heterogeneous catalyst?
those which exist in a different phase from the reaction being catalysed.
When the Keq > 1 which reaction is favoured?
- forward
- backward
When Keq > 1 the forward reaction is favoured.
what factors affect the rate of the reaction?
pressure, temperature and concentration
Calculate the value of the equilibrium constant, Kc, for the system shown, if:
0.1908 moles of CO2 0.0908 moles of H2
and 0.0092 moles of H2O vapour were present in a 2.00 L reaction vessel were present at equilibrium.
What is the reaction quotient?
the ratio of concentrations of the products of a reaction with the concentrations of the reactants
aA + bB –> cC + dD
the reaction quotient is?
Why is the reaction quotient used in stead of the equilibrium expression?
Q gives the same ratio the equilibrium expression gives, but for a system that is not at equilibrium.
What kind of reaction is this?
an endothermic reaction.
what is the second arrow representing?
energy absorbed
what does the y axis represent?
potential energy
What is the arrhenius equation? and what does it calculate?
rate constant
k = Ae - Ea / (RT)
How do you calculate the Q - Reaction Quotient?
K is what?
rate constant
If Q> K what happens to the equation?
the reaction goes from right to left where reactants are preffered over products
What is Le Chatelier’s Principle?
If we change the conditions factors such as the ones mentioned above of a reaction system in equilibrium, the system will shift in such a way as to reduce the imbalance caused by the stress. Examples of stresses include increasing or decreasing chemical concentrations or temperature changes.
Which side will be favoured? given the pressure increases.
The forward reaction because the forward reaction will because it will result in less moles of gas.
name three ways in which pressure can be changed in a system to affect the chemical reaction at equilbrium
a) increasing the volume, therefore lowering the pressure
b) decreasing the volume thereby increasing the pressure.
c) raising the total pressure by adding an inert (non-reacting) gas
Would adding a catalyst to anything to a chemical reaction at equilibrium?
yes it would if a change in pressure, concentration or temperature is first implemented
to the right
which way will the reaction equilibrium shift?
to the left
left
neither because each side has the same amount of moles
neither, both are sped up
to the right
what happens here at ?
the equilibrium is reestablished
the habers process is ___exo/endo thermic?
exothermic
recycled
how is an equilibrium pushed to the right in this reaction of the Haber process
by removing ammonia and also increasing pressure and lowering temperature
what happens at the cathode and what happends at the anode?
reduction occurs at the cathode and oxidation at the annode
what is the electromotive force?
the potential difference between two electrodes. This can be measured using a voltmeter.
the maximum voltage of a cell can be calculated using experimentally determined values called ___ ___ ___?
standard electrode potentials.
how is the emf calculated?
the standard electrode potentials of the reactions.
calculate the emf of the cell based on the following net reaction
