Key points

Question 1

Which compound is the least polar?

Answer 1

-pure hydrocarbons, then ethers, etc. charged compounds or with H bonds or extra electrons are polar (ie. an ether less polar than a carbocation)

Question 2

Can a monosubstituted benzene ring act as an electrophile?

Answer 2

NO because aromatic compounds do not undergo nucleophilic aromatic substitution thus can only act as nucleophiles

Question 3

When are two compounds diastereoisomers?

Answer 3

They have same stereochemistry on one stereocenter and opposing stereochemistry on the other. Cis/trans and E/Z compounds also display diastereoisomers

Question 4

When do we use cis/trans and when E/Z notation?

Answer 4

Cis/trans used for rings and E/Z for alkenes

Question 5

what is an acyl halide?

Answer 5

-C0Cl functional group (don’t confuse with alkyl halide which is a haloalkane)

Question 6

How can we convert directly from nitrobenzene to (p)4-chloro-1-nitrobenzene?

Answer 6

We cannot directly do this; NO2 is meta directing

Question 7

Define rate constant

Answer 7

proportionality constant (k) in rate law ie. For first order reaction rate, rate proportional to k (A)

Question 8

Define first order reaction

Answer 8

Where the overall reaction order in the rate law is 1. The rate is directly proportional to the concentration of a reactant (rate=k(A))

Question 9

define half life

Answer 9

the time take for the concentration of a reactant to fall to half of its initial value (give equation for 1st order R half life)

Question 10

Define a heterogeneous/homogeneous catalyst

Answer 10

Catalysts are substances that speed up a reaction without being used up in the overall process. A heterogeneous catalyst is in a different phase to the reactants. For example Pt (solid) in the hydrogenation of alkenes (gas)
A homogeneous catalyst is in the same phase as the reactants (ie. gas catalyst in a gaseous reaction) homogeneous catalysts usually appear in rate law

Question 11

Define transition state in an elementary reaction

Answer 11

Transition state in an elementary reaction is the point of highest energy between reactants and products (marked so# in a reaction profile-must draw a diagram to support this)

Question 12

Explain the terms average and instantaneous rate

Answer 12

Average rate is the change in rate over a time interval (change in conc over time). However instantaneous rate is the rate at a specific point in time during the course of the reaction (give by a tangent to the curve of the conc vs time plot-must give a diagram for both)

Question 13

define rate law

Answer 13

relationship between rate and concentration (ie.rate proportional to (A))

Question 14

Define rate constant

Answer 14

proportionality constant in the rate law (give example)

Question 15

define a third order reaction

Answer 15

Where the overall reaction order in the rate law is three. The rate is 3rd order in a single reactant or 2nd order in 1 and 1st order in another or 1st order in 3 reactants (and write the three possible equations)

Question 16

Define activcation energy

Answer 16

Activation energy is the energy required by the reactants to reach the transition state (draw a diagram and label both Ea and #)

Question 17

Define arrhenius equation

Answer 17

Arrhenius equation gives the relationship for the temperature dependence of the reaction rate constant (give the equation)

Question 18

acid anhydride functional group

Answer 18

-COOOC-

Question 19

nitrile fucntional group

Answer 19

NN (triple bond)

Question 20

acyl vs alkyl halide

Answer 20

-COCl (acyl halide), -CCl (alkyl halide)

Question 21

Enantiomers

Answer 21

mirror images of each other( have opposing stereochemistry at all stereocenters)

Question 22

What happens when more than one functional group is present?

Answer 22

Name based on O containing functional group

ie. pent-3-en-2-one

Question 23

Explain chromatography

Answer 23

Molecules separated based on polarity. Polar solutes are more attracted to the polar stationary phase and move slowly while non-polar are less attracted to the polar phase of the stationary phase and therefore move more rapidly (with the non-polar solvent)

Question 24

Nucleophiles

Answer 24

Electron donors; are either -vely charged or neutral and will have either lone pairs of electrons or electrons in p bonds

Question 25

Electrophiles

Answer 25

Electron acceptors; can be neutral (have a polar bond) or +vely charged

Question 26

How do we calculate number of Hs?

Answer 26

(2 (C)+ 2)-(2*DBE)+1(N) -1(Halogen)

Question 27

In which order do we write the atoms in the molecular formula?

Answer 27

1st C then H, the rest follow with alphabetical order