Slides in this set
s i s
c t r oly
Using an electric current to split a
compound, either in a solution or a
Electrolyte: When the ions reach the
A liquid compound that breaks down At the Cathode (- electrode) positive ions are electrodes, they are
when electricity is passed through it. discharged, and at the anode (+ electrode) discharged. They then turns
To make it a liquid it can be melted negative ions are discharged.
dissolve in water. into atoms and molecules.
OPTIMUM CONDITIONS: Positive ions move toward the cathode and Cations = negative ions
The optimum conditions depends on negative ions move toward the anode. Anions = positive ions
different factors, but the conditions
which do get considered "optimum" is The cathode gets heavier because it is plated and Reduction will always occur
how long the current flows for and the the anode gets lighter as it dissolves.
size of the current. at the cathode. The cathode
However cathode weight and anode weight are will become heavier because
the same amount at the start. of this.
Amount of substance
produced at an electrode
increases with current and
The charge effects the
amount of ions discharged.…read more
l l s ADVANTAGES OF FUEL CELLS FUEL CELLS IN SPACECRAFTS
-More efficient -Waste very little energy
el -Direct energy transfer -Lighter than normal
Fu -Less polluting, as no
nitrogen oxides are produced
-Fuel cells weigh less, makes
batteries, the spacecraft can
use saving to carry a bigger
FUEL CELLS IN THE CAR things lighter and less -They can be used
INDUSTRY expensive to run continuously
-More efficient than normal -Water produced is not
engines wasted, it is drunk by the
-Large sources of hydrogen pilots
by decomposing water -They do not need a special
-Less pollution fuel with its own storage
-Less nitrogen oxides, which system (the spacecraft has to
produces less smog carry hydrogen and oxygen
-Hydrogen is a gas, which is anyway for it's rocket
harder to store in a car engines)
-Fuel pumps will need to be
A special type of electric.
They don't need replacing or
recharging, they will need to
WHAT ARE FUEL CELLS?
Fuel cells are very efficient…read more
a c tio ord equat
io n fo r a d isplaceme
When a w , t h e m o r e reactive al. Mg
written ive met
reaction is ' with the less react
o x ces
`swaps pla ive than Zn so Zn is
is more re
m + Zinc S
u lp h a t e -> Magnesiu
A word made up from 2 processes that work
together (reduction and oxidation)
A type of redox reaction: iron
+ oxygen + water->hydrated iron (III) oxide
Galvanising: Displacement occurs with reactive metals and a compound of a less
It protects iron from rusting by covering it with reactive metal.
a layer of zinc. All metals react by pushing off electrons and turning into ions. This is
-the layer of zinc stops water and oxygen from oxidation.
reaching the surface of the iron. -These electrons are forced onto the ions of other metals that are
-zinc also acts as a sacrificial metal, as it is more not as reactive
reactive than the iron. -Metal atoms that gain these electrons are reduced
Iron coated with tin which acts as a barrier. It is less reactive so loses
electrons even faster causing rusting. However if it is coated with a
thin layer of Zn or Mg then it will rust a lot slower, because they are
both more reactive than iron, so lose electrons in preference to iron,
these are known as sacrificial metals and the process is called
Jesus in a way acts like a sacrificial metal, people are the Iron and
God is the weather…read more
rmulae and th
o l s Both the m o le cu la
o f a lc ohols with 1 to
displayed form the table
A l c o C a rb
s are shown in
re a re many more a
Ethanol is made by the process of fermentation. Only e
carefu anol is ma
The balanced equation for fermentation is: If the controlled by fermen
· Glucose Ethanol + Carbon Dioxide yeast temperatur onditions. tion, under
· CHO 2CHOH + 2CO If the e inactive. is too low,
yeast temperatur zymes
are de e is to in
If air n a o high, t
Ethanol is made by the fermentation of Glucose solution. is pres tured. he en
produ e zymes
· The reaction is catalysed by the enzymes in yeast. cing e nt, there is in
· This will only happen if there is no Oxygen present. ethan thano a differe
ol. ic acid nt rea
· The dilute liquid produced undergoes fractional d of
distillation to produce ethanol.
The alcohols are a group of compounds which have the
general formula CnHn+OH
Ethanol that is used in industry can also be made
Methods of Ethanol Production: from ethene. Ethanol made in this way is a non-
renewable fuel because the ethene it is made from
comes from fossil fuels.
This reaction to make ethanol from ethene is known
as a hydration reaction because water is added to
the ethene molecule; ethene + water ethanol.
Ethene and steam are passed over a hot phosphoric
The balanced symbol equation for the hydration
reaction is; CH + HO CHOH…read more
n e L ay e r ( 1 )
n o f t he Oz o
Depl e t i o
The more depleted the layer of
ozone gets, the more UV light can
ith The O
get through the Earth's surface.
a n b e re placed w z
There one layer i
CFC's c a si
alkanes o carbons which this la re only tin n the strat
yer, h y amo o
ro the U owev unts o sphere.
Hydrofluo age the ozone V rad e
am iation r it still ab f Ozone in
will not d from so
the su rbs most o
layer. n. f
UV radiation is part of the EM
spectrum. Visible light can pass
through the ozone layer easily,
but UV radiation is absorbed by it.
When CFC's were first discovered, -The UV part of the
they were thought to be totally electromagnetic spectrum has
safe. exactly the right frequency to
-Scientists now know that CFC make ozone molecules vibrate.
molecules slowly move upward into -The energy of the UV radiation is
the stratosphere where they attack converted into movement energy
the ozone layer. inside each molecule.
-Society agreed with the scientists' -The thicker the ozone layer, the
views that it is CFCs that deplete more UV radiation is absorbed.
the Ozone layer. That is why the When CFC's were discovered in
use of CFC's has been banned in the the 1930's, scientists were excited
UK but it is a global problem. because these substances were
inert. In the 1970'ss scientists
began to link the depletion of the
ozone layer with CFC's…read more
n e L ay e r ( 2 )
n o f t he Oz o
Depl e t i o
When a covale
In the stratosphere, the UV radiation from the nt body
breaks it can
Sun breaks down the CFC molecules to give split into
equal halves to
highly reactive chlorine atoms. A single make
chlorine atom is called a chlorine radical.
-These chlorine atoms react with Ozone
molecules, turning the ozone back into
Oxygen gas and depleting the ozone layer.
-Chlorine atoms are regenerated so they can
react with more ozone molecules.
UV lights breaks down CFC's very slowly, so
Uv radiation causes radicals. Each radical sets off a chain reaction. One
they last a long time.
chlorine radical causes the breakdown of more than 100,000 ozone
CFCl CFCl + Cl.
The chain reaction has three stages:
1. Uv light breaks a bond in CFC molecules to form chlorine radicals.
o C FC's orine, 2. Chlorine radicals react with ozone molecules, creating more chlorine
r na tives ntain c so are radicals
lte t co nd Cl. + O OCl. + O
e s for a 's don' adicals a
a i n choi C's. HFC lorine r OCL. + O Cl. +2O
m HF ch Combining these two equations gives: 2O 3O
The es and t make
n o 3.One possible termination is: Cl. + C. Cl
alka ey cann
safe CFC's take around 20-5o years to be broken down so although they
have been banned they still have effect.…read more