Key Stuff - Module 3 + 5 Flashcards by Millie Hansgate

1st ionisation energy

removal of 1 mole of electrons from 1 mol of gaseous atoms

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Periodicity

Repeating trends in physical + chemical properties

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Metallic bonding

Strong electrostatic attraction bt/w positive ions + delocalised electrons

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Disproportionation

Oxidation + reduction of the same element

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Activation Energy

Minumum energy required for a reaction to take place

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Enthalpy change of formation

Formation of 1 mol of compound froms its elements

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Enthalpy change of combustion

Compete combustion of 1 mol of a substance

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Enthalpy change of neutralisation

Formation of 1 mol of water from neutralisation

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Average bond enthalpy

Breaking of 1 mol of bonds in gaseous molecules

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Homogenous catalyst

Same phase a reactants

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Heterogeneous catalyst

Different phase as reactants

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Bronsted-Lowry acid

Donates a proton

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Bronsted-Lowry Base

Accepts a proton

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What indicator should you use for strong acid + strong base reaction

Phenolphalein or methyl orange

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Strong acid + weak base

Methyl orange

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Weak acid + strong base

Phenolphthalein

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Weak acid + weak base

pH at equivalence - depends on the relative strength of acid + base

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Lattice enthalpy

Formation of 1 mol of ionic lattice from gaseous ions

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Enthalpy change of solution

Dissolving of 1 mol of solute

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Enthalpy change of hydration

Dissolving of 1 mol of gaseous ions in water

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Entropy

Measure of dispersal of energy in a system which is greater, the more disorder a system

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Standard electrode potential

Electromotive force compared to standard hydrogen electrode
Standard condition: 298K, 1mol dm-3, 100kPa

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Units for rate constant (k)

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Rate graphs for 0 order reaction

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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

1. Form redox equation 2. FInd the moles of compound 3. Use redox equation to find the moles of unknown 4. 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

1. Hydrogen gas enters system 2. Hydrogen oxidised to H+ at anode 3. Electrons travel via external circuit 4. H+ ions travel through electrolyte + membrane 5. oxygen gas enters cell 6. Oxygen is reduced at cathode 7. Catalyst speeds up reaction bt/w oxygen + H+ 8. 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?

1. Cr3+ (within [Cr(OH)6]3- which is dark green) oxidised to yellow CrO4 2- by warming with H2O2 in alkaline conditions 2. Add H2SO4 to CrO4 2- produces orange dichromate (Cr2O7 2-) 3. (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

What does the value of Kc tell you about where the equilibrium lies

- If Kc < 1 - equilibrium lies towards reactants - If Kc = 1 - equilibrium lies midway bt/w reactants + products - If Kc > 1 - equilibrium lies towards products

What factors affect + how Kc/Kp

- Temperature: If ↑temp shifts in endothermic direction, if bac reaction endothermic ↑ amount reactants + ↓ products - Kc/Kp ↓ - Depends on which way exo/endo can work it out by writing out equation, seeing if top or bottom ↓ then work out if that give you a bigger or smaller number (see p138) - Concentration + pressure DO NOT affect Kc/Kp

Describe the set up of hydrogen-oxygen fuel cell

- Hydrogen is at the anode + oxidised - Oxygen is at the cathode + reduced

What is the main difference bt/w acid or alkali hydrogen-oxygen fuel cell

Acid: - H+ ions flow from left to right Alkali: - OH- ions flow from right to left