Key Stuff - Module 3 + 5 Flashcards
1st ionisation energy
removal of 1 mole of electrons from 1 mol of gaseous atoms
Periodicity
Repeating trends in physical + chemical properties
Metallic bonding
Strong electrostatic attraction bt/w positive ions + delocalised electrons
Disproportionation
Oxidation + reduction of the same element
Activation Energy
Minumum energy required for a reaction to take place
Enthalpy change of formation
Formation of 1 mol of compound froms its elements
Enthalpy change of combustion
Compete combustion of 1 mol of a substance
Enthalpy change of neutralisation
Formation of 1 mol of water from neutralisation
Average bond enthalpy
Breaking of 1 mol of bonds in gaseous molecules
Homogenous catalyst
Same phase a reactants
Heterogeneous catalyst
Different phase as reactants
Bronsted-Lowry acid
Donates a proton
Bronsted-Lowry Base
Accepts a proton
What indicator should you use for strong acid + strong base reaction
Phenolphalein or methyl orange
Strong acid + weak base
Methyl orange
Weak acid + strong base
Phenolphthalein
Weak acid + weak base
pH at equivalence - depends on the relative strength of acid + base
Lattice enthalpy
Formation of 1 mol of ionic lattice from gaseous ions
Enthalpy change of solution
Dissolving of 1 mol of solute
Enthalpy change of hydration
Dissolving of 1 mol of gaseous ions in water
Entropy
Measure of dispersal of energy in a system which is greater, the more disorder a system
Standard electrode potential
- Electromotive force compared to standard hydrogen electrode
- Standard condition: 298K, 1mol dm-3, 100kPa
Units for rate constant (k)
Rate graphs for 0 order reaction
Rate graphs for 1st order
Rate graphs for 2nd order
Rate determining step info
- Slowest step is rate determining step
- Species involved in this step are found in overall rate equation
Weak acids
Partially dissociate into ions in aqueous solutions
Strong acids
Completely dissociate into ions in aqueous solutions releasing H+ ions
Name 3 basic strong acids
- HCl
- HNO3
- H2SO4
Name a basic weak acids
Carboxylic acids eg ethanoic acid
Name 3 basic strong bases
- NaOH
- KOH
- Ba(OH)2
Name a weak base
Ammonia (NH3)
State the redox reaction bt/w manganate (VII) + iron (II)
Describe the method you would use to do a redox titration calculation
- Form redox equation
- FInd the moles of compound
- Use redox equation to find the moles of unknown
- Scale up if needed
What must you remember when calculating elctrode potential
Reduced electrode potential is always more positive electrode potential
Explain the process of a proton exchange fuel cell
- Hydrogen gas enters system
- Hydrogen oxidised to H+ at anode
- Electrons travel via external circuit
- H+ ions travel through electrolyte + membrane
- oxygen gas enters cell
- Oxygen is reduced at cathode
- Catalyst speeds up reaction bt/w oxygen + H+
- Water produced
Advantages of fuel cells
- Eliminate pollution caused by burning fossil fuels
- Eliminates green house gases if hydrogen used comes from electrolysis of water
- Higher efficiency than diesel or gas engines
Alkaline Fuel Cells (AFC)
- Uses alkaline electrolyte eg KOH
- Used by NASA in space shuttles
Direct Methanol Fuel Cells (DMFC)
- Uses polymer membrane as electrolyte
- Catalyst on anode draes hydrogen from liquid methanol
- Eliminates need for fuel reformer, pure methanol can be used as fuel
Rearranged Arrhenius equation for Ea
Ea = RT (lnA-lnk)
Rearranged Arrhenius equation for A
Rearranged Arrhenius equation for T
T = Ea / R (lnA-lnk)
Ligand
Particle with lone pair thay forms a coordinate (dative covalent) bond to metal
Complex
Central metal ion with ligands coordinately bonded to it
Coordination number
Number of coordinate bonds from ligand to metal ions
Cis-platin
- Anti-cancer drug
- Complex of platinum (II) with X2 chloride ions + X2 ammonia molecules in square planar shape
- Binds to DNA preventing cell division
Unidentate ligands
- Donates one electron pair
- Form one coordinate bond
- Eg. [Cu(H2O)6]2+
Bidentate ligands
- Donates X2 electron pairs
- Form two coordinate bonds
- Eg. [Cr(NH2CH2CH2NH2)3]3+
Multidentate ligands
- Donates several electron pairs
- Form several coordinate bonds
- Eg. [Cu(EDTA)]2-
Ti 3+
Purple
Ti +2
violet
VO2 + (OS +5)
Yellow
VO2+ (OS +4)
Blue
V3+
Green
V2+
Violet
Cr2O7 2- (OS +6)
Orange
Cr3+
Pale purple
Looks green in aqueous solutions
MnO4 - (OS +7)
Purple
MnO4 2- (+6)
Green
Mn2+
Pale pink
Fe3+
Yellow
Fe2+
Pale green
Co2+
Pink
Ni2+
Green
Cu2+
Pale blue
Explain what is meant by the term buffer solution?
- Buffer solution minimises pH changes
- On the addition of small amounts of acid or alkali
How do you reduce Cu2+ & what is the colour change?
- With I-
- pale blue → white ppt but brown solution due I2
What transition metal ion spontaneously disproportionates?
- Cu
- 2Cu+ → Cu + Cu2+
- In aqueous conditions
What is involved in the interconversion bt/w Fe2+ & Fe3+ & what is the colour change?
- Fe2+ oxidised by (yellow) acidified KMnO4 (aq)
What is the standard redox equation bt/w Fe and KMnO4?
How do you reduce Fe3+ & what is the colour change?
- With I-
- yellow/brown → pale green
What is involved in the interconverstion bt/w Cr3+ & Cr2O7 2- & what is the colour change?
- Cr3+ (within [Cr(OH)6]3- which is dark green) oxidised to yellow CrO4 2- by warming with H2O2 in alkaline conditions
- Add H2SO4 to CrO4 2- produces orange dichromate (Cr2O7 2-)
- (Cr2O7 2-) reduced to Cr3+ (green) by acidified zinc
What is electron configuration of Ti?
What is the electron configuration of V?
What is the electron configuration of Cr?
What is the electron configuration of Mn?
What is the electron configuration of Fe?
What is the electron configuration of Co?
What is the electron configuration of Ni?
What is the electron configuration of Cu?
Describe the relationship bt/w acid strength an pKa + Ka?
The stronger the acid the higher Ka but lower pKa
