CHEMISTRY Flashcards
what happens in electrolysis?
requires a liquid to conduct electricity
Positive ions move towards negative electrodes
what does electrolysis extract? and what does it do and what is required?
metals more reactive than carbon.
makes it pure
high temperature & energy
what are the advantages of quarrying?
- used as building materials
- limestone products from thermal decomposition used to neutralise soils
- used in power station chimneys to neutralise sulphur dioxide
what are the disadvantages of quarrying?
- permanently changes the landscape
- noise and dust pollution
what other 2 methods could we use to extract small bits of copper?
low grade ores - bioleaching and phytomining
how does bioleaching work?
bacteria gets energy from bond between copper and sulfur separating out the copper. Leachate is produced containing copper and extracted by filtering
how does phytomining work?
low grade ore
grow plants in soil containing copper, builds up in leaves, plants harvested and burnt in a furnace, copper collected from ash.
where is crude oil from?
buried remains of plants and animals
advantages of crude oil?
good fuels for transport
reliable
cheap
what are the disadvantages of crude oil?
non-renewable
oil spills- birds poisoned
causes global warming and acid rain
what are 3 alternatives fuels for crude oil?
ethanol
biodiesel
hydrogen gas
how is ethanol produced?
produced from plant material made by the fermentation of plants
what are the pros of the alternative fuel of ethanol?
carbon neutral and it’s only other product is water - no pollution
what are the cons of ethanol fuel?
engines need to be converted and isn’t widely available
how is the alternative fuel biodiesel produced?
by vegetable oils & rapseed oils
what are the pros and cons of biodiesel?
carbon neutral, produces less sulphur dioxide & engines don’t need to be converted
expensive
how is hydrogen gas produced?
electrolysis of water
what are the pros of hydrogen gas?
very clean only forms water
need special expensive equipment & isn’t widely available
what is cracking?
long chain molecules like diesel into short chain molecules like petrol paraffin and ethene
what type of reaction is cracking?
thermal decomposition
what are the conditions needed for cracking? what are the products?
high temperature to vaporise it then passed over a catalyst. produces alkenes
what is polymerisation?
joining lots of alkenes together
how do you convert ethene to ethanol? pros, cons?
hydrated with steam in presence of a catalyst.
cheap
ethene is produced from a non renewable resource
how else could you get ethanol but from renewable resources?
fermentation - sugar (from plants) = carbon dioxide + ethanol
how do you get oils from plants?
plant material is crushed, then you press the crushed plant and squash the oil out.
what are the uses of extracting oils from plants?
provides humans energy, high boiling point than water - cook foods faster, rapeseed oil turned into biodiesel
why would you use the method hydrogenating on oils?
most are runny at room temperature - not useful
how is the process of hardening: hydrogenating done?
reacted with hydrogen in the presence of a nickel catalyst at 60c - makes them saturated
what 3 things does recycling metals do?
saves energy
saves natural resources
less pollution
what type of fats are less healthy?
saturated
what uses do polymers have?
plastic bags
memory foams for beds - smart polymers
what are the pros and cons of polymers?
cheap
nonbiogradable, from crude oil and its non-renewable so prices will rise.
what are the transition metals
ones in the middles
what are the symbols for calcium hydroxide?
Ca(OH)2
how is calcium hydroxide formed?
adding water to calcium oxide
why might iron be converted to steel?
iron is brittle
steel is strong / flexible
what is limestone heated in?
rotary lime kiln
what products are formed from adding water and sand to limestone?
cement or mortar
if you then add crushed rocks?
concrete
metals unreactive are found in their?
native state, most are found as metal ores and need to extracted
what is alloying?
adding small amounts to other elements - can improve properties as now has a irregular structure
what is crude oil a mixture of?
hydrogen and carbon
gases in the air can?
be separated from
fractional distillation for use in industry.
what does the earths atmosphere consist of?
nitrogen 80%
oxygen 20%
co2 0.037%
other gases 0.9%
in a emulsifier is the tail hydrophilic? what is it attracted to?
YES
attracted to WATER
name the order of the alkenes?
methane - CH4
Ethane
propane
butane
what properties does a shorter molecule have?
the less viscous it is - more runny
more volatile - turn into gas at lower temperature
more flammable
what is complete combustion
all the fuels burn
what is formed from partial combustion
solid particulates of soot & carbon monoxide
what causes global dimming
soot & ash - reflect sunlight back
what do you get when you add a LOT of water to slaked calcium hydroxide?
calcium hydroxide solution - limewater
what can limewater be tested for?
carbon dioxide- if it’s present so is limestone - bringing it back to the start of the calcium carbonate
what is the core of earth made out of?
iron and nickel
what was in the earths early atmosphere?
volcanoes added lots of c02 water and nitrogen
cooled and condensed into the oceans
plants appeared and photosynthesised to absorb the c02 and release oxygen
how would you test for an unsaturated hydrocarbon?
add bromine water, will turn from orange to colourless
what makes unsaturated hydrocarbons?
cracking
what makes saturated hydrocarbons?
crude oil from fractional distillation
when metal carbonates react with acids what is formed?
salt water and carbon dioxide
how is iron removed from its ore?
mix iron oxide and carbon in a blast furnace- reduction of carbon
carbon displaces the iron because it’s more reactive
we so this because iron oxide is originally in the ore
what is titanium used for?
medical implants
strong but not corrosive
what is the equation for complete combustion?
hydrocarbon + oxygen = carbon dioxide + water ALWAYS MAKES THAT
what is the equation for incomplete combustion?
hydrocarbon + 1.5oxygen = carbon monoxide + water
are alkenes saturated?
NO
which are the most useful hydrocarbons?
short chain molecules - why cracking is done
monomers are always?
alkenes
