gcse science chemistry unit C6 part 1
- Created by: charlie
- Created on: 07-05-13 21:03
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- C6
- fuel cells
- fuel + O2 makes energy
- hydrogen oxygen fuel cell
- redox reaction
- efficiency 80% and direct energy
- producing H2 needs power and H2 contains poisonous catalyst- money to get rid of
- in spacecraft
- electricity
- lightweight and waste water reused
- in car industry
- only heat and water produced
- hydrogen made by decomposing water (electrolysis)
- rusting of Fe
- redox
- iron + oxygen +water = hydrated iron (III) oxide
- stopping rusting
- oil and grease paint
- physical barrier
- tin
- physical barrier but less reactive
- iron + more reactive metal
- sacrificial metal Zn Mg
- alloys
- stainless steel
- oil and grease paint
- redox reactions
- OIL RIG
- both oxidation and reduction happen at same time
- displacement reactions
- Fe - 2e' = Fe2+
- 2H+ + 2e' = H2
- oxidising agent
- reducing agent
- 2H+ + 2e' = H2
- CFC's and ozone layer
- first- good, non toxic, non flammable, inert
- 1974- Cl destroys O3
- 1978- banned USA, Canada, Sweden
- 1985- hole over Antarctica and every country reduced use
- 1978- banned USA, Canada, Sweden
- 1974- Cl destroys O3
- 1) CCL2F2 = CCLF2 + Cl.
- 2) O3 + Cl. = CLO. +O2
- free radicals
- covalent bond breaks even and each atom shares e'
- CFC's stay around one molecule reacts with thousands of O3
- refrigerants and propellants
- breakdown
- O3+UV=O+O2
- O+O2=O3
- O3+UV=O+O2
- alternatives
- alkanes
- dont react with O3
- HFC's
- no chlorine
- alkanes
- first- good, non toxic, non flammable, inert
- electrolysis
- splitting up with electricity
- H2SO4 (aq)
- H2 ions
- +ve
- ions go to cathode gain e'
- 2H+ +2E'=H2
- +ve
- OH' ions
- -ve
- ions go to anode lose e'
- 4OH' - 4e'=O2+2H2O
- -ve
- H2 ions
- electrons transferred
- increases with time
- increases with current
- Q=IT(s)
- increases with time
- Q=IT(s)
- fuel cells
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