Exam 2

Question 1

Equation to find Kc?

Answer 1

Kc = [product A]^moles x [product B]^moles DIVIDED BY [reactant A]^moles x [reactant B]^moles

Question 2

What is Kc?

Answer 2

Equilibrium Constant

Question 3

How is partial pressure calculated?

Answer 3

{(number of moles A)/(total moles of gas)} x total pressure of mixture

Question 4

What is Kp?

Answer 4

Equilibrium Constant calculated using partial pressures

Question 5

What does and doesn’t affect Kc/Kp?

Answer 5

Pressure does not
Catalysts do not
Temperature does

Question 6

What kind of reaction do arenes undergo?

Answer 6

Electrophilic Substitution

Question 7

Alkylation of Benzene?

Answer 7

Chloroalkane + Benzene + AlCl3 under Reflux

Question 8

Acylation of Benzene?

Answer 8

Acyl Chloride + Benzene + AlCl3 under Reflux

Question 9

What is AlCl3 an example of?

Answer 9

Halogen Carrier

Question 10

Substitution of halogen into Benzene?

Answer 10

Halogen carrier and dimer - dimer is polarised by halogen carrier, d+ then acts as electrophile

Question 11

Advantages of ionic liquids as solvents?

Answer 11

Less volatile
Less flammable
Less toxic
Easier to reuse

Question 12

What is an azo group?

Answer 12

-N=N-

Question 13

Colour change in dichromate reflux?

Answer 13

Orange to Green

Question 14

What has to be formed before an azo dye?

Answer 14

Diazonium salt -N(+)tripleN-

Question 15

What is standard lattice enthalpy?

Answer 15

Enthalpy change when 1 mole of a solid ionic compound is formed from its gaseous ions under standard conditions

Question 16

What is enthalpy change of hydration?

Answer 16

Enthalpy change when 1 mole of aqueous ions is formed from gaseous ions

Question 17

What is enthalpy change of solution?

Answer 17

Enthalpy change when i mole of solute is dissolved in sufficient solvent that no further enthalpy change occurs on further dilution

Question 18

What does Total entropy change equal?

Answer 18

Enthalpy change of system + Enthalpy change of surroudings

Question 19

What does ^S system equal?

Answer 19

S products - S reactants

Question 20

What does ^S surroundings equal?

Answer 20

-(^H/T) where ^H is enthalpy change in Jmol-1 and T is temp in Kelvin

Question 21

What does entropy change have to be for a spontaneous reaction to take place?

Answer 21

Positive

Question 22

What is pH?

Answer 22

-log10[H+]

Question 23

How to find [H+] of strong base?

Answer 23

(1x10^-14)/[OH-]

Question 24

What is equilibrium concentration?

Answer 24

= ([H+][A-])/[HA] using the assumption [H+] = [A-]

Question 25

What does pKa =?

Answer 25

-log10Ka

Question 26

What are acid buffers made from?

Answer 26

A weak acid and one of its salts

Question 27

What is -SO3H

Answer 27

Sulfonic Acid

Question 28

What is the best way of dye attaching to fabric?

Answer 28

Acid group donate H+ ion to NH group in fabric and the resulting dye ion is held in place by ionic bond

Question 29

What is a chromophore?

Answer 29

The structure in a molecule that give it colour

Question 30

How can you modify the colour of a dye?

Answer 30

Add groups with O or N atoms. Lone pairs become part of the delocalised system of electrons

Question 31

How can you modify the solubility of a dye?

Answer 31

Addition of soluble functional groups such as Sulfate ion

Question 32

How is benzene halogenated?

Answer 32

Halogen carrier polarise dimers. 
Positively charged end acts as an electrophile. 
Forms HBr (e.g.) and halogen carrier is unchanged.

Question 33

How is benzene nitrated?

Answer 33

Warm with conc nitric and conc sulfuric acid

Sulfuric is catalyst - helps form NO2+ ion (the electrophile)

Question 34

How is benzene sulfonated?

Answer 34

Reflux with conc sulfuric
OR
Warm with fuming sulfuric acid (contains lots of SO3, the electrophile)
O gets neg charge and attacks the H, so H doesn’t leave. Forms benzenesulfonic acid O=S(=O)-OH

Question 35

How is benzene alkynated?

Answer 35

Chloroalkane refluxed with AlCl3 to form an alkyl carbocation which acts as an electrophile

Question 36

How is benzene acylated?

Answer 36

Acyl chloride given carbocation by reflux with AlCl3, acts as electrophile

Question 37

How to make azo dye?

Answer 37

Nitrous acid used to produce diazonium salt, with HCl
Dissolve phenol with NaOH. React with diazonium salt when stood in ice. Azo dye precipitates out.
Temp kept below 10* at all times.

Question 38

What splits 3d orbitals?

Answer 38

Ligand bonding

Question 39

More delocalisation means what for energy levels?

Answer 39

Smaller