The Ozone Story Flashcards
What two requirements must there be for hydrogen bonding to occur?
•A δ+ hydrogen atom directly covalently bonded to a N,O,F
•A highly electronegative atom (N,O,F) with a lone pair that can attract the δ+ hydrogen
What is the overall equation for the breakdown of ozone?
O3 + O -> 2O2
What is a nucleophile?
A species with a lone pair of electrons, which it can donate to a δ+ carbon to form a new covalent bond
In what instance are half curly arrows used?
During homolytic fission to form radicals; movement of one electron to each atom on the bond
Define: ‘substitution reaction’
Where one atom or group in a molecule gets replaced by another atom or group
Give the sequence of steps involved in purifying an organic product
Neutralise -> Wash with water -> Siphon off aqueous layer -> Add anhydrous sodium carbonate -> Distill
What are the two requirements for a molecule to have a permenant dipole?
•Polar covalent bond (ie two elements very different in electronegativity)
•Of which, there is an overall dipole as the polar bonds do not cancel out
What is a catalyst, what does it do and how does it do this? (2)
Catalysts speed up a reaction and can be recovered chemically unchanged at the end (1). They provide an alternative reaction pathway with lower activation energy (2)
Why does increasing the temperature increase the rate of a reaction? (2)
•Particles have more kinetic energy, so are moving faster, leading to more frequent collisions (1)
•And a much higher proportion of collisions will occur at or above Ea (2)
What is activation enthalpy?
The minimum energy required by a pair of two colliding particles to result in a reaction
What are the four requirements for a hydrogen bonding diagram?
1 - δ+ on hydrogen and δ- on N,O,F
2 - Lone pair on N,O,F
3 - Dotted line between N,O,F and δ+ hydrogen (Not continuous line)
4 - Bond is 180°
State whether chloromethane or bromomethane has the higher boiling point and explain why this is
Bromomethane has the higher boiling point. This is because the bromine atom has more electrons that can fluctuate so stronger instantaneous dipole-induced dipole bonds despite chlorine being more electronegative so stronger permenant dipole-permenant dipole bonds
What is the method for finding the minimum frequency to break a covalent bond in nm, by using knowledge of the bond’s enthalpy?
•Convert kjmol –> jmolecule
•Divide this by planck’s constant to get frequency
•Divide the speed of light by this to get wavelength
•Multiply the answer by 1×10^9
When drawing enthalpy diagrams, what feature must the arrows NOT have present?
Double heads; only one head and it should be facing up
What are the four marking points for every hydrogen bonding diagram? (4)
• Correct atoms AND dashed line for hydrogen bond (1)
• δ+/δ- in correct places (2)
• Lone pair on N/O/F facing the bond (3)
• 180° angle between one of the covalent bonds and the hydrogen bond (4)
