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OZ Flashcards

(55 cards)

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1
Q

What does ppm stand for?

A

Parts per million
- refers to vey small concentrations of gas

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2
Q

The ozone layer is in the ________?

A

Stratosphere

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3
Q

What are some gases produced by human activities?

A
  • carbon dioxide
  • methane
  • nitrous oxide
  • carbon monoxide
  • nitrous oxides
  • chlorofluorocarbons
  • hydrofluorocarbons
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4
Q

What is the conversion between % and ppm?

A

1% = 10,000ppm

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5
Q

What are the energies a molecule can have?
Start with lowest energy

A
  • translation- the molecule moving around as a whole
  • rotation- of the molecule
  • vibration- of the bonds within the molecule
  • electron energy
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6
Q

Describe vibrational energy

A

The kinetic energy
- corresponds to infrared

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7
Q

What part of the spectrum does rotational energy correspond with?

A

Microwave

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8
Q

What part of the spectrum does electron energy correspond to?

A

Visible and ultraviolet

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9
Q

what are the three ways that a molecule can absorb energy?

A
  • electrons excited to higher level
  • photodissociation to create a radical
  • molecule is ionised
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10
Q

Define a radical

A

A species with an unpaired electron

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11
Q

Describe heterolytic fission

A

When a covalent bond breaks to form one cation and one anion
- one atom gets both electrons
- common when bonds are polar

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12
Q

Describe homolytic fission

A

When a covalent bond breaks to form 2 radicals
- two species of same type
- each atom gets electron
- common in non-polar bonds
- known as photodissociation

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13
Q

What do full full headed arrows show?

A

The movement of a pair of electrons

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14
Q

What do half headed arrows show?

A

The movement of one electron

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15
Q

What are the three stages in a radical chain reaction (mechanism)?

A
  • Initiation
  • propagation
  • termination
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16
Q

Describe initiation

A
  • first radical is formed by homolytic fission
  • 1 reaction
  • radicals on product side of reaction
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17
Q

Describe propagation

A
  • initial radicals react with substances to produce more radicals
  • reactions will feed into each other
  • 2 reactions
  • radicals on either side of equation
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18
Q

Describe termination

A
  • two radical collide
  • 3 reactions
  • radicals on reactant side
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19
Q

Alkanes react with halogens to create ___________

A

Haloalkanes

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20
Q

Define a steady state

A

When a product is being used up as fast as it is produced

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21
Q

What are the ways in which rate of reaction can be measured?

A
  • measuring volumes of gases evolved
  • measuring mass change
  • measuring pH
  • colorimetry, measure change in colour
  • chemical analysis throughout
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22
Q

What factors affect the rate of reaction?

A
  • concentration
  • pressure, in gases
  • temperature, speeds up particles and increases energy
  • particle size
  • catalyst
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23
Q

Describe collision theory

Study These Flashcards
A
  • reactions occur when correctly orientated particles collide with a certain minimum energy to react
24
Q

If you increase reaction rate, you have ____________________________________

Study These Flashcards
A

MORE FREQUENT SUCCESSFUL COLLISIONS

25
Define activation enthalpy
The minimum kinetic energy required by a pair of colliding particles before a reaction will occur
26
What does a catalyst do?
Provides an alternate reaction pathway of lower activation energy
27
Define rate of reaction
The change in concentration of a reactant or a product ina given time
28
Define the Boltzmann distribution
The distribution of energies of molecules at a given temperature
29
Area under a distribution curve will ___________ as temperature stays constant
Remain constant
30
Define electronegativity
A measure of the attraction of a bonded atom for the pair of bonding electrons in a covalent bond
31
true or false: carbon-haloge bonds are polar
True
32
When do polar bonds form/
When atoms attract bonding electrons unequally - polarity will depend on the electro negativity differences
33
intermolecular bonds are ________ molecules
Between
34
Dipoles depend on….
The electro negativity differences and the shape of the molecule
35
Define a permanent dipole
A small charge difference across a bond, resulting from a difference in the electronegativo ties of the bonded atoms
36
Define a polar molecule
Has an overall dipole when you take into account any dipoles across the bonds
37
Define intermolecular force
An attractive force between neighbouring molecules
38
Describe instantaneous dipoles
- temporary as electrons are always moving so at any moment there many be and imbalance of electrons, causing a charge
39
Describe induced dipoles
Occur when an unpolarised molecule is next to a dipole
40
describe instanteous dipole-induced dipole forces
- IDIDs - they are the only attractive intermolecular force acting between non-polar molecules - AKA van der waals - caused by interaction between temporary dipoles - weakest type of intermolecular bonding
41
Descriv=be permanent dipole-permanent dipoles
A permanent dipole-dipole force is a weak attractive force between permanent dipoles in neighbouring polar molecules
42
What are the 4 intermolecular bond types?
- IDIDBs - permanent dipole-permanent dipole - permanent dipole - induced dipole - hydrogen bonds
43
Describe hydrogen bonding
- a special type of permanent dipole- permanent dipole - strangest intermolecular bond type - must have a large dipole, small hydrogen atom, lone pair of electrons
44
Define viscosity
-a measure of how easily a liquid flows
45
How are hydrogen bonds drawn?
- a dotted line between molecule and lone pair - show dipoles
46
How is water arranged in ice
In a open lattice arrangement - causes ice to be less dense than water due to hydrogen bonds holding molecules apart
47
Define a hydrogen bond
a strong dipole-dipole interaction between; - an electron deficient hydrogen atom on one molecule and.. - a lone pair of electrons on a highly electronegative atom on a different molecule
48
Describe heterolytic fission
- breaking of a (polar) bond to form two different species - more common under normal laboratory conditions - carbon-halogen bonds will break to form a negative halide ion and a carbocation
49
Define substitution
A reaction in which one atom or group in a molecule is replaced by another tom or group
50
What happens in a nucleophilic substitution reaction?
A nucleophile replaces another group
51
Define nucleophile
A molecule or negatively charged ion with a lone pair of electrons that it can donate to a positively charges atom to form a covalent bond
52
What are examples of nucleophiles?
- water, has two lone pairs, hydrolysis reactions, produces alcohol - ammonia, haas one lone pair, produces an **amine** - halide ion, produce a haloalkane, done in presence of strong acid - hydroxide ion -
53
What decides the reactivity of a substance?
Bond enthalpy/strength - polarity DOES NOT
54
A nucleophile will _________ the carbocation
ATTACK
55
What are the steps of a nucleophilic substitution?
- the nucleophile attacks the electron deficient carbon - the nucleophile donates a pair of electrons to formation dative covalent bond - this then breaks the C-X bond by heterolytic fission - the X- is the **leaving group**

Chemistry (7 decks)

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