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15 Cards in this Set
- Front
- Back
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what is a catalyst
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it is a substance that lowers the activation energy needed for a reaction to occur by providing an alternative route without being used up in the process. it speeds up the reaction
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what is meant by half life
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it is the time taken for half of the radioactive nuclei to decay
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what is entropy
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it is the measure of the different ways particles in a subtance can be arranged.
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what is hess law
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energy change is the same no matter what route is taken as long as the inital an final conditions are the same
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what is the equation for hess law
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route 1 = route 2 + route 3
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what is a mole
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a mole is 6.02 x 10 (23) particles and is equal to the same amount of particles in 12 grams of carbon 12
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what is an emission spectrum
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previsouly excited elctrons fall down to their ground state whilst emitting energy worth the distance travelled between the shells . the energy relates to frequency in the equation E=hv. the lines are unique to an element
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what is clean buring
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when you have complete combustion taking place where the products are mainly only C02 and H20
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what is octane number
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it is the likelyhood of a substance to auto ignite. A high rating means it will be less likely to auto ignite.
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What is the difference between empirical and molecule formula
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it shows the smallest whole number ratioof atoms in a compound. molecular shows you the actual number of atoms
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what are the two functional groups
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alkene (cyclohexane) and an alcohol (0H)
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When is the formula Q= MxCxT used and what does each part stand for
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used to measure enthalpy change (heat water by burning flammable liquid)
q= heat transferred (loss/gain) (J) M=mass C= heat capacity T= the change in temp ( final - initial) |
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Time of flight mass spectrometerflight
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sample turned into a gas , it is then ionised by high energy electrons as they bombard them knocking off electrons (makes it positive), ions are accelerated by an electric field, they are then deteched at the end . time taken for ion to reach detector depends on size (small=fast)
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what is nuclear fusion
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Nuclear fusion is when two small nuclei combine - high temperture and high pressures (occurs in stars)
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how does a hetrogeneous catalyst work
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molecules arrive at surfaceand bond with catalyst ( ADSORPTION) bonds between reactant weaken/breaks up forming RADICALS. RADICALS join together and form new bonds. new molecule detaches from catalyst(DESORPTION)
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