Karteikarten
aqa as chemistry unit 2
Karten in diesem Stapel (34)
- 1Initiation in free radical subsproduction of free radicals
- breaks homolytically
- photochemical reaction - 2Propagationreaction between a free radical and a molecule to make another free radical
- 3Termination (FRS)reaction between two free radicals making an unreactive molecule
- 4Standard enthalpy of formationthe enthalpy change when one mole of a compound is formed from its constituent elements in their standard states, under standard conditions
- 5why is the enthalpy of formation of oxygen gas zero?it is an element, in its standard state
- can be applied to all other elements - 6Mean bond enthalpyStandard molar enthalpy change of bond dissociation is the energy required to break a specific covalent bond. This varies between compounds, so an average is used
- 7Standard enthalpy change of combustionEnthalpy change when one mole of a compound is completely burnt in oxygen under standard conditions
- 8Enthalpy changeHeat energy change measured at constant pressure
- 9Hess's Lawthe enthalpy change for a reaction is independent on the pathway taken from the reactants to products
- 10Oxidation (in terms of electrons)loss of electrons
- 11Reduction (in terms of electrons)gain of electrons
- 12Oxidising power - trend in the halogens- decreases going down the group
- want to gain electrons. This is shown by displacement reactions - 13Halide ions as reducing agents- increases going down the group
- want to lose electron
- larger = easier to lose electron - 14Halogens - Ionic radiusincreases going down the group, increasing reducing power
- 15why is the ionic radius larger than the normal atom? (in negative ion)added electron repels others so radius gets larger
- 16Disproportionationredox reaction in which the oxidation number of some atoms of a particular element increases and others of the same element decrease
- 17conditions needed for elimination- no water present
- hydroxide is dissolved in ethanol and mixed with haloalkane
- hot
- tertiary haloalkane - 18conditions needed for nucleophilic subs- presence of water
- cold
- primary haloalkane - 19geometrical isomersame structural formula but bonds are arranged differently in space
- 20why are alkenes not used as fuels?their reactivity makes them useful for other purposes
- 21electrophile- attracted to double bond
- electron pair reciever
- form carbocations - 22positive inductive effectalkyl groups e.g. CH3 or C2H5 have a tendency to release electrons
- 23Electrophilic addition steps1. formation of carbocation by electrophilic additon
2. rapid reaction with a negative ion - 24define: polymer- long chain molecule made from many monomers
- forms a chain with a very high Mr - 25why do alcohols have higher melting and boiling points than alkanes of a similar Mr?addition of -OH means that there is hydrogen bonding between molecules
- 26why are shorter chain alcohols soluble in water?hydrogen bonding means that hydrogen bonds can form between water and -OH
- 27Temperature- the average kinetic energy of particles in a system
- particles move faster, KE goes up and so does temp
- temperature is independent of the number of particles present - 28Heat- total energy of all particles present
- dependent of amount of substance present
- flows from high to low temp - 29Specific heat capacityamount of heat needed to raise the temperature of 1g of substance by 1K
- 30How does a flame calorimeter reduce heat loss?- spiral chimney is made of copper
- flame is enclosed
- fuel burns in pure oxygen, rather than in air - 31bond dissociation energythe enthalpy change required to break a covalent bond with all species in a gaseous state
- 32Gangueunwanted materials from ores such as clay and rock
- 33Orean ore is a substance that contains enough metal for it to be economically viable to mine and extract
- 34Roastingprocess of converting sulfide ores to oxides by heating in air
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- Karteikarten am aqa as chemistry unit 2 , erstellt von jamie_m am 25/05/2015.
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