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1
Q

How do van deer waals forces arise?

A
  • uneven distribution of electrons
  • creates instantaneous dipole
  • causes an induced dipole on neighbouring molecule
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2
Q

Define molecular formula

A

Actual number of atoms of each element present in a molecule

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3
Q

How can you tell a salt has been formed?

A

Hydrogen ion replaced by metal ion

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4
Q

Define ionic lattice

A

Repeating pattern of oppositely charged ions

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5
Q

Define electronegativity

A

Ability of atom to attract electrons in a covalent bond

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6
Q

What is a base

A

Substance that readily accepts H+ ions

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7
Q

What is an alkali

A

Substance that releases OH- ions into solution

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8
Q

How are catalysts good for environment

A

Lower temp can be used - reduces co2 emissions

Reduces use of toxic reactants

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9
Q

Define enthalpy change

A

When one mole of bonds is broken

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10
Q

What makes a molecule polar

A

Not symmetrical so dipoles don’t cancel out

Difference in electronegativities

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11
Q

State hess’ law

A

The enthalpy change of a reaction is independent to the route it takes

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12
Q

Define standard molar enthalpy of formation

A

The energy change when one mole of compound is formed from is constituent elements in standard state

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13
Q

What do m and z stand for

A

Mass

Charge

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14
Q

What is the chemical name for bicarbonate of soda?

A

Sodium hydrogen carbonate

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15
Q

What is a heterogeneous equilibrium?

A

Reactants in a different state

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16
Q

Why is boiling point of PH3 lower than boiling point of AsH3?

A

AsH3 has more electrons

Stronger induced dipole-dipole interactions

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17
Q

What are the stages of reducing a haloalkane to primary amine?

A

Haloalkane
Nitrile
Primary amine

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18
Q

What does Hess’ law state?

A

The enthalpy change accompanying a chemical change is independent of the route by which the chemical change occurs

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19
Q

What is a dynamic equilibrium?

A

Rate of fowards reaction equals the rate of backwards reaction

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20
Q

What does aromatic mean?

A

The compound contains a benzene ring

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21
Q

What are the three types of structural isomer?

A

Chain, positional, functional group

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22
Q

What is a sigma bond?

A

A single covelant bond made up of two shared electrons with the electron density concentrated between the two nuclei

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23
Q

What is a pi bond?

A

Formed by the side ways overlap of two p orbitals on adjacent carbon atoms, each one providing one electron

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24
Q

What is a radical?

A

A particle with an unpaired electron

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25
Why are alkenes unreactive?
The C-H bonds have very low polarity | C-H bonds are relitavley strong
26
What determines highest priority in E/Z isomerism
Atomic number
27
Reaction conditions for Hydration of ethene
Water with phosphoric acid at 300 degrees with high pressure
28
Conditions to dehydrate an alcohol
Conc sulfuric acid and Al2O3
29
What does the dehydration of an alcohol give?
An alkene
30
Conditions to hydrolyse a haloalkane
the solvent must be in water and must be heated under refulx
31
How can you rest the trend in rates of reaction in haloalkanes?
Mix with water and silver nitrate Heat Monitor the rate at which precipitate forms.
32
What affects ionisation energy?
Atomic radius Nuclear charge Shielding effect
33
What is the most reactive halogen?
Fluorine
34
Fluorine oxidises water to give what>
HF and O2
35
What colour is iodine in cyclohexane?
Purple
36
What colour is bromine in cyclohexane?
Orange
37
What colour is chlorine in cyclohexane?
pale yellow
38
Equation for pka
-logKA
39
Equation for KA
10-pka
40
How can you distinguish between stereo isomers?
Plane polarised light rotated equally in opposite directions
41
How do you convert gdm-3 into mol dm-3
gdm-3 divided by mr
42
How do van der waals forces arise?
Unequal distribution of electrons causes instantaneous dipole Causes induced dipole on neighbouring molecules
43
What are some issues of making chiral drugs?
Enantimors could be toxic | Have to seperate 1:1 ratio of enantimors
44
How does GC-MS allow products to be identified?
Seperates compounds and comparison with a data base
45
What is the chemical responsible for the peak at 0 in NMR and why is it added?
TMS | Standard for chemical shift measurement
46
Show how ALCl3 behaves as a catalyst
AlCL3 + Cl2 --> AlCl4- + Cl+ | H+ + AlCl4- ----> AlCl3 + HCl
47
Reagents needed for reduction og 1,4-dinitrobenzene
Tin and conc HCl
48
Define the term lattice enthalpy
The energy change that takes place when one mole of ionic compound is formed from its constituent ions in gaseous state
49
Explain why it is difficult to predict whether the lattice enthalpy of magnesium bromide would be more or less exothermic than the lattice enthalpy of sodium chloride
Mg has a greater charge and therefore greater charge density than sodium Bromine has smaller atomic radius However not paired with eachother
50
Would the entropy change of magesium with dilute sulfuric acid be positive or negative?
Positive as a gas is formed which is more disordered
51
Would the entropy change of the complete combustion of ethane be positive or negative?
Negative | 9 mol of gas to 4 mol of gas so less disordered
52
How can a sutible indicator be chosen from looking at a pH titration curve graph?
Chose the indicator that changes in the vertical section
53
Steps to purify 2-hydroxybenzoic acid
``` Dissolve in the minimum amount of hot solvent Cool in ice bath forming crystals Vacuum filtration using buchner flask Rinse with cold solvent Dry in oven ```
54
Why does bromine have a higher boiling point than chlorine?
Bromine has more induced dipole interactions
55
Why does water expand when it is frozen?
H bonds in ice hold H2O molecules further apart
56
Why does the production of chloromethane by radical substitution produced a very low percentage yield?
further substitution occurs
57
Why are C-C bonds all the same in benzene?
Pi bonds are delocalised
58
How can IR distinguish between ketones and carboxylic acids?
Carboxylic acids have a broad O–H absorption at 2500–3300
59
Why is the rate of hydrolysis of 1-bromobutane is faster than that of 1-chlorobutane.
C-Br bond is weaker
60
Units for ideal gas equation
T in K V in m3 p in Pa

Chemistry (16 decks)

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