Exam 2 Flashcards
Equation to find Kc?
Kc = [product A]^moles x [product B]^moles DIVIDED BY [reactant A]^moles x [reactant B]^moles
What is Kc?
Equilibrium Constant
How is partial pressure calculated?
{(number of moles A)/(total moles of gas)} x total pressure of mixture
What is Kp?
Equilibrium Constant calculated using partial pressures
What does and doesn’t affect Kc/Kp?
Pressure does not
Catalysts do not
Temperature does
What kind of reaction do arenes undergo?
Electrophilic Substitution
Alkylation of Benzene?
Chloroalkane + Benzene + AlCl3 under Reflux
Acylation of Benzene?
Acyl Chloride + Benzene + AlCl3 under Reflux
What is AlCl3 an example of?
Halogen Carrier
Substitution of halogen into Benzene?
Halogen carrier and dimer - dimer is polarised by halogen carrier, d+ then acts as electrophile
Advantages of ionic liquids as solvents?
Less volatile
Less flammable
Less toxic
Easier to reuse
What is an azo group?
-N=N-
Colour change in dichromate reflux?
Orange to Green
What has to be formed before an azo dye?
Diazonium salt -N(+)tripleN-
What is standard lattice enthalpy?
Enthalpy change when 1 mole of a solid ionic compound is formed from its gaseous ions under standard conditions
What is enthalpy change of hydration?
Enthalpy change when 1 mole of aqueous ions is formed from gaseous ions
What is enthalpy change of solution?
Enthalpy change when i mole of solute is dissolved in sufficient solvent that no further enthalpy change occurs on further dilution
What does Total entropy change equal?
Enthalpy change of system + Enthalpy change of surroudings
What does ^S system equal?
S products - S reactants
What does ^S surroundings equal?
-(^H/T) where ^H is enthalpy change in Jmol-1 and T is temp in Kelvin
What does entropy change have to be for a spontaneous reaction to take place?
Positive
What is pH?
-log10[H+]
How to find [H+] of strong base?
(1x10^-14)/[OH-]
What is equilibrium concentration?
= ([H+][A-])/[HA] using the assumption [H+] = [A-]
What does pKa =?
-log10Ka
What are acid buffers made from?
A weak acid and one of its salts
What is -SO3H
Sulfonic Acid
What is the best way of dye attaching to fabric?
Acid group donate H+ ion to NH group in fabric and the resulting dye ion is held in place by ionic bond
What is a chromophore?
The structure in a molecule that give it colour
How can you modify the colour of a dye?
Add groups with O or N atoms. Lone pairs become part of the delocalised system of electrons
How can you modify the solubility of a dye?
Addition of soluble functional groups such as Sulfate ion
How is benzene halogenated?
Halogen carrier polarise dimers. Positively charged end acts as an electrophile. Forms HBr (e.g.) and halogen carrier is unchanged.
How is benzene nitrated?
Warm with conc nitric and conc sulfuric acid
Sulfuric is catalyst - helps form NO2+ ion (the electrophile)
How is benzene sulfonated?
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
How is benzene alkynated?
Chloroalkane refluxed with AlCl3 to form an alkyl carbocation which acts as an electrophile
How is benzene acylated?
Acyl chloride given carbocation by reflux with AlCl3, acts as electrophile
How to make azo dye?
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.
What splits 3d orbitals?
Ligand bonding
More delocalisation means what for energy levels?
Smaller
