C6.1 Flashcards
what are the three essential elements needed by plants?
nitrogen, phosphorus and potassium
what happens is plants have limited supply of their essential elements in the soil?
they will show signs of mineral deficiency and the quality and yield of food will be reduced
what are the symptoms of plants if they are nitrogen deficient?
poor growth and yellow leaves
what are the symptoms of plants if they are phosphorous deficient?
poor root growth and discoloured leaves
what are the symptoms of plants if they are potassium deficient?
poor fruit growth and discoloured leaves
what are fertilisers?
substances added to soil that replace elements and nutrients used by plants as they grow
in what conditions can plant roots only absorb elements ?
if they are in a water soluble form
what does: nitrogen ammonium phosphorus potassium have to be in order for plants to be able to absorb them?
nitrate ions - NO3 -
ammonium ions - NH4 +
phosphate ions - PO4 3-
potassium ions - K +
what is the name for fertilisers that provide nitrogen, phosphorus and potassium in water soluble compounds known as?
NPK fertilisers
what is the Haber process?
an industrial process to make ammonia from nitrogen an hydrogen
what is the chemical equation for the Haber process?
N2(g) + 3H2(g) <=> 2NH3 (g)
how many tonnes of ammonia are manufactured in the world per year?
150 million
what are the raw materials required for the Haber process?
air, natural gas and steam
how is nitrogen manufactured?
by fractional distillation of liquefied air (air is 98% nitrogen)
how is hydrogen manufactured?
by reacting natural gas (mostly methane) with steam
what happens in a fertiliser factory?
several different processes are integrated so a range of compounds for fertilisers can be made
name 4 compounds for fertilisers that can be created in a fertiliser factory
1) ammonium nitrate - NH4NO3
2) ammonium sulfate - (NH4)3SO4
3) ammonium phosphate - (NH4)3PO4
4) potassium nitrate- KNO3
what are the 4 steps to making potassium sulfate in a lab?
1) put dilute potassium hydroxide into a conical flask and add a few drops of phenolphthalein indicator to enable you to determine when the alkali has been neutralised
2) add dilute sulfuric acid from a burette or dropping pipette stopping when the indicator changes from pink to colourless
3) add activated charcoal which attracts the phenolphthalien and then filter the mixture to remove the charcoal and phenolphthalein attached to it
4) heat filtrate to make water evaporate leaving potassium sulfate behind but it shouldn’t be heated to dryness
what can potassium sulfate be made from?
potassium hydroxide and sulfuric acid
what are the 3 steps of making ammonium sulfate in a lab?
1) place dilute ammonia solution in a conical flak with methyl orange indicator
2) add dilute sulfuric acid from a burette or dropping pipette stopping when the indicator changes from yellow to red
3) when you reach the end point add a little extra ammonia solution to ensure the reaction is complete and any remaining ammonia will be lost in evaporation
what are the hazards with making ammonium sulfate in the lab?
1) ammonia solution releases small amounts of ammonia in gas state which has an irritating sharp smell so you have to try not breath it in
2) excess ammonia is given off in the gas state when the solution is warmed
what is the batch process? when is it used?
a chemical process that makes products in limited amounts at different times and is used in the lab
what is the continuous process? when is it used?
chemical process that makes products in large amounts at a time and is used in industrial processes and are rarely shut down
what is the difference between the materials used in a laboratory and the materials used in fertiliser factories?
laboratories use pure substances bought from a chemical manufacturer but fertiliser factories use raw materials that are either purified before or after the reaction
what is the difference between the rate of production in the batch process vs the continuous process?
batch has low rate continuous has high
what is the difference between the relative cost of equipment in the batch process vs the continuous process?
batch is low continuous is high
what is the difference between the number of workers needed in the batch process vs the continuous process?
batch has a large number but continuous has low
what is the difference between the shut down periods in the batch process vs the continuous process?
batch have frequent shut down periods while continuous are rare
what is the difference between the ease of automating the process in the batch process vs the continuous process?
batch is low and continuous is high
what are the conditions used for the Haber process? (temperature and pressure)
pressure of 200 atmospheres (20 MPa)
temerature of 450C
what type of catalyst is used in the Haber process?
iron catalyst
what yield do the conditions usually chosen for the Haber process create?
a 30% equilibrium yield of ammonia
what would happen if the pressure increased in the chosen conditions fro the Haber process?
the equilibrium yield of ammonia would increase but it would be hazardous and expensive and the higher yield wouldn’t justify the additional costs of the high pressure
what type of reaction is the forward reaction of the Haber process?
exothermic
what type of reaction is the backward reaction of the Haber process?
endothermic
what would happen if you increased the temperature of the chosen conditions of the Haber process?
the equilibrium yield would decrease
why is 450C chosen as the temperature for the Haber process?
because it is a compromise. low enough to achieve a reasonable equilibrium yield but high enough to achieve reasonable rate of reaction
what temperature does the catalyst in the Haber process work at best?
400C
why are the mixture of gases in the Haber process cooled?
so that the ammonia is liquefied allowing it to be removed and the un-reacted nitrogen and hydrogen to be recycled improving the overall yield to 97%
what are the 3 raw materials required to make sulfuric acid?
sulfur, air and water
what happens in the first stage of creating sulfuric acid?
sulfur burns in air to produce sulfur dioxide
what is the equation for the first stage of creating sulfuric acid?
sulfur + oxygen -> sulfur dioxide
S (s) + O2(g) -> SO2(g)
what is the name of the second stage of creating sulfuric acid?
the contact process
what is the contact process
the industrial process that makes products in large amounts over time
what happens in the contact process?
sulfur dioxide and oxygen react together to produce sulfur trioxide
what is the equation for the contact process?
2SO2(g) + O2(g) <=> 2SO3(g)
what are the conditions usually chosen for the contact process when making sulfur trioxide? (pressure/temp/catalyst)
pressure of 2 atmospheres (200 kPa)
temperature of 450C
vanadium oxide catalyst
what is the yield in the chosen conditions for creating sulfur trioxide when making sulfuric acid?
98%
what happens in the third stage of making sulfuric acid?
sulfur trioxide is converted into sulfuric acid
what is the equation for he third stage f making sulfuric acid?
water + sulfur trioxide -> sulfuric acid
H2O(l) + SO3(g) -> H2SO4 (aq)
what would happen if you increased the chosen pressure for the reaction creating sulfur trioxide?
it would be unnecessary because 2 atmospheres is enough to push the gases through the converter and 3 is not necessary
what would happen if you increased the temperature of the reaction to create sulfur trioxide?
the equilibrium yield of sodium trioxide would decrease as a high equilibrium yield is favoured by a low temperature
why is the temperature of 450C chosen when creating sodium trioxide?
it is a compromise that is low enough to achieve a reasonable equilibrium yield but a high enough rate of reaction and the catalyst only works above 380 C
why is stage three of creating sulfuric acid carried out in two pahses?
because it is an extremely exothermic reaction that would produce a hazardous acidic mist
what is the first stage of the third phase of creating sulfuric acid?
sulfur trioxide is passed through concentrated sulfuric acid to make a compound called oleum
what is the equation for the first stage of the third phase of creating sulfuric acid?
H2SO4(l) + SO3 (g) => HS2O7 (l)
what is the second stage of the third phase of creating sulfuric acid?
the oleum created in the first phase is then added to water and the reaction makes a larger volume of concentrated sulfuric acid
what is the equation for the second stage of the third phase of creating sulfuric acid ?
H2S2O7 (l) + H2O (l) => 2H2SO4 (aq)
what are renewable raw materials?
materials that can be replaced as they are used and in theory should not run out
what is ethanol made from?
plant sugars using fermentation
how is ethanol made? (renewable)
yeast cells are single celled fungi and catalyse the conversion of glucose solution into carbon dioxide and ethanol
what is the equation for making ethanol? (renewable)
glucose -> carbon dioxide + ethanol
C6H12O6 (aq) -> 2CO2 (g) + 2C2H5OH (aq)
what happens if the temperature is too low or too high when using yeast?
the yeast cells become inactive if it is too low and denature if it is above 50C
what conditions is fermentation carried under?
35C and normal atmospheric pressure (100 kPA)
what are non renewable raw materials?
material that can be used faster than they can be replaced and will run out one day if you continue using them
how is ethanol made? (non renewable)
it is obtained from crude oil which is non renewable and can be produced through the hydration of ethene
what is hydration?
a reaction where water is added
what is the equation fro making ethanol? (non renewable)
ethene + steam -> ethanol
C2H4 (g) + H2O (g) <=> C2H50H (g)
where can renewable ethanol be produced?
in the lab and with industrial fermentation with more complex equipment but the same conditions
where can non renewable ethanol be produced?
only as an industrial process
what are the conditions required for creating non renewable ethanol? temperature/pressure/catalyst
temperature of 300C
pressure of 60 atmospheres
catalyst of phosphoric acid
what is the difference between the cost of raw material for fermentation of sugars vs hydration of ethene?
fermentation is a low cost but hydration is a high cost
what is the difference between the conditions for fermentation of sugars vs hydration of ethene?
fermentation : moderate temperature and normal pressure
hyrdation: high temperature and pressure
what is the difference between the energy requirements for fermentation of sugars vs hydration of ethene?
fermentation requires low energy but hydration requires high
what is the difference between the rate of reaction for fermentation of sugars vs hydration of ethene?
fermentation has a low rate but hydration has a high rate
what is the difference between the percentage yield for fermentation of sugars vs hydration of ethene?
fermentation : low - 15%
hydration: high - 95%
what is the difference between the purity of the product produced for for fermentation of sugars vs hydration of ethene?
fermentation: low - needs filtering and fractional distillation
hydration: high - there are no by-products
what will the choice for production of ethene depend upon?
- availability of materials
- cot of materials
- cost of energy required
what is an ore?
a rock or mineral that contains enough metal/metal compound to make it economical to extract the metal
what metal compound is found in the ore malachite?
copper carbonate
what metal is found in the ore bauxite?
aluminium oxide
what metal is found in the ore haematite?
iron (III) oxide
what must happen to an ore in order to separate a metal from an ore?
the ore must be mined and processed to separate the metal from the other substances in the ore. the metal is extracted from the pure metal compound using a chemical reaction
what does the method of extracting a metal from its ore depend upon?
the position of the metal in the reactivity series
what type of met to extract metal from an ore if the metal is less reactive than carbon?
cheaper methods are used
why isnt electrolysis used to extract all metals?
because it is an expensive process
how are copper and iron extracted from their ores?
they are extracted by heating their compounds with carbon or carbon monoxide because they are less reactive than carbon
how many stages are required to extract copper from copper sulfide?
two
what happens in the first stage of extracting copper from copper sulfide?
coper(ll) sulfide is “roasted” in air
what is the equation for roasting copper sulfide in the first phase of extracting copper from copper sulfide?
copper(ll) slufide + oxygen -> copper(ll) oxide + sulfur dioxide
2CuS (s) + 3O2 -> 2CuO (s) + 2SO2
what happens in the second stage of extracting copper from copper sulfide?
copper (II) oxide it heated with carbon
what is the equation for heating copper oxide with carbon in the second stage of extracting copper from copper sulfide?
copper (II) sulfide + oxygen -> copper + carbon dioxide
2CuS(s) + 3O2(g) -> 2Cu(s) +CO2(g)
what types of reaction is the one for extracting copper from copper sulfide?
it is a redox reaction
why is the reactions of extracting copper from copper sulfide a redox reaction?
because copper looses oxygen and is reduced and carbon gains oxygen and is oxidised and in the reaction carbon is acting as a reducing agent
what three gases can you heat copper (II) oxide with to get copper?
methane, hydrogen and carbon(after burning in air)
what is used to extract iron from its ore?
a large industrial reaction container called a blast furnace
how much iron do modern blast furnaces produce each day?
10000 tonnes per day
what 3 raw materials are added to the top of blast furnaces and why are they added?
1) iron ore such as haematite which contains iron(III) oxide
2) coke
3) limestone to purify the iron
how is coke made?
it is made up of mostly carbon made by heating coal in absent air
what is the main reducing agent in a blast furnace?
carbon monoxide although carbon can reduce iron(III) oxide into iron
how many stages are there to producing iron in a blast furnace?
three
when is carbon monoxide produced in a blast furnace?
when coke reacts with carbon dioxide
what happens in the first stage of producing iron in a blast furnace?
coke burns in hot air making carbon monxide
what is the equation for the first stage of producing iron in a blast furnace?
C(s) + O2(g) ->CO2 (g)
what happens in the second stage of producing iron in a blast furnace?
more coke reduces the carbon dioxide making carbon monoxide
what is the equation for the second stage of producing iron in a blast furnace?
C(s) + CO2(g) -> 2CO(g)
what happens in the third stage of producing iron in a blast furnace?
carbon monoxide reduces iron(III) oxide to form iron at around 1500C
what is the equation for the third stage of producing iron in a blast furnace?
3CO(g) + Fe2O3(s) -> 3CO2(g) + 2Fe(l)
what happens after the three stages of producing iron in a blast furnace?
the molten iron trickles downwards in the blast furnace
why does the molten iron have to be purified by limestone after it has been produced by the blast furnace?
because it contains sandy impurities from the iron ore
how many stages are there to purifying molten iron from a blast furnace with limestone?
two
why is limestone used to purify molten iron from a blast furnace?
because it mostly contains calcium carbonate
what happens in the first stage of purifying molten iron from a blast furnace with limestone?
calcium carbonate decomposes in the high temperature
what is the equation for the first stage of purifying molten iron from a blast furnace with limestone?
CaCO3(s) -> CaO(s) + CO2(g)
what happens in the second stage of purifying molten iron from a blast furnace with limestone?
the calcium oxide formed in the first stage reacts with silica from the sandy impurities to form calcium silicate
what is the equation for the second stage of purifying molten iron from a blast furnace with limestone?
CaO (s) + SiO2(g) -> CaSiO3 (l)
what is the name for molten calcium silicate formed from purifying molten iron from a blast surface with limestone?
slag
what happens once the molten iron from the blast furnace has been purified?
the slag floats on top and both are removed separate from the bottom of the blast furnace
how does aluminium exist naturally? what ore is it found in?
exists naturally as aluminium oxide Al2O3 found in the ore bauxite
how reactive is aluminium in comparison to carbon? what does this mean about the process which must be used to extract it?
its more reactive so has to be extracted using electolysis
what problem is there with using electrolysis for separating aluminium from its ore?
electrolysis only works if the compound is in solution or molten but aluminium doesn’t dissolve in water and has a very high melting point
what is the melting point of aluminium? why is it hard to heat it to this temperature?
over 2000 C and it would be extremely expensive to heat it to this temperature
what happens in order for aluminium to be separated from its ore?
it is dissolved in molten cryolite which has a lower meting point than aluminium
what temperature can electrolysis of aluminium happen at if cryolite is used?
950 C
what is the aluminium oxide and cryolite contained in when electrolysis takes place?
a huge electrolysis cell made from steel lines with graphite
what part of the apparatus used in electrolysis of aluminium oxide acts as the cathode?
the graphite lining of the cell acts as the negative electrode
what part of the apparatus used in electrolysis of aluminium oxide acts as the anode?
the series of large graphite blocks placed in the electrolyte act as the positive electrodes
what is produced at the cathode in electrolysis of aluminium oxide?
aluminium
what is produced at the anode in electrolysis of aluminium oxide?
oxygen
what is produced when oxygen reacts with the large graphite anodes?
carbon dioxide
what usually happens to mines when they are abandoned?
they flood
what happens when mines flood?
metal sulfides oxidise under water producing sufuric acid which reacts with other metal ores forming soluble metal compounds which leave with the water as it drains from the mine
what can cause the reaction of metal ores to react faster?
bacteria
what happens in bio-leaching?
bacteria oxidise iron(II) and sulfide ions and use the energy transferred and form sulfuric acid in the presence of water and oxygen
what happens to the sulfuric acid produced by bio-leaching?
it breaks down copper sulfide ores and other minerals releasing copper(II) ions and other metal ions
what is bio-leaching?
biological method of extracting metals in which bacteria speed up reactions that release soluble metal compounds from metal sulfides
name 3 benefits of bio-leaching
1) it is cheaper than traditional methods of mining and processing
2) you can extract metals from low grade ores that would be unprofitable to extract normally
3) the bacteria occur naturally and don’t need any special treatment
4) it doesn’t release harmful sulfur dioxide into the atmosphere
name 2 disadvantages of bio-leaching
1) it is slow
2) toxic substances such as sulfuric acid can be produced which could escape into water supplies/ the soil
what is phytoextraction?
a biological method of metal extraction in which plants absorb metals through their roots and concentrate them into their cells
what are the steps to phytextraction?
1) crops are planted in soil containing a low grade ore or mine
2) a complexing agent is added if necessary so the plants can absorb the metal ions easier
3) the plants are harvested and then burned to produce an ash with a high concentration in the metal
4) the bio-ore is smelted(extracted) to yeild metal
what are the advantages of phytoextraction? name 3
1) cheaper than traditional mining and processing
2) produces less waste
3) involves smaller energy transfers
4) close to being a carbon neutral activity
5) can contribute to sustainable development
what are the disadvantages of phytoextraction?
1) slow
2) crops may need replanting and harvesting for several years before available metal is removed from the soil
how is phytoextraction close to being carbon neutral?
burning plants release carbon dioxide but they also absorb carbon dioxide for photosynthesis as they grow
what is carbon neutral?
a process where there is no overall release of carbon dioxide into the atmosphere
what is an alloy?
a mixture f two or more elements and at least one of which is a metal
what is steel?
an alloy where iron is mixed with other metals and carbon
name 2 properties of steel
high tensile strength and ductile
what is tensile strength?
the measure of how strong a metal is when stretched
name 5 alloys
1) steel
2) duralumin
3) solder
4) brass
5) bronze
what is the main metal in steel?
iron
what are the typical uses of steel?
buildings, bridges and cars
what are the main 2 metals in duralumin
aluminium and copper
what is druralumin normally used for?
aircraft parts
what are the main 2 metals in solder?
tin and copper
what are the typical uses of solder?
joining electrical components and copper pipes
what are the 2 main metals in brass?
copper and zinc
what are the typical uses of brass?
musical instruments and coins
what are the 2 main metals in bronze?
copper and tin
what are the typical uses of bronze?
bells and propellers for ships
what is the melting point of tin?
232C
what is the melting point of copper?
1085C
what is the meting point of solder?
227C
how is the melting point of solder useful when joining electrical components?
it joins it without damaging it as the hot solder in the liquid state flows into the gaps between the electrical components and solidifies quickly and allows an electrical current to pass through
what happens to metal particles when they are bent or stretched?
layers of metal atoms slide oer eachother
why are alloys stronger and harder than the individual metals themselves?
the atoms are different sizes making it more difficult for the atoms to slide over each other
name 3 properties of brass. what do these properties make brass useful for?
1)hard/strong
2)good conductor of electricity
3)resists corrosion
makes it useful for making pins for electrical plugs
name 3 properties of bronze which makes it better than copper
1) resists corrosion
2) stronger/ harder thin copper
why is bronze useful for metal artwork?
it expands slightly as it solidifies so fills in tiny details in an artists mould
what is corrosion?
the reaction of a metal with substances in its surroundings such as air and water
what is special about the corrosion of silver?
silver doesn’t corrode easily with oxygen in the air or water but will corrode in the presence of hydrogen sulfide (H2S)
what naturally produces hydrogen sulfide?
bacteria
what happens when silver reacts with hydrogen sulfide?
hydrogen sulfide reacts with silver when water and oxygen are also present producing a thing layer of black silver sulfide (Ag2S)
what metals don’t corrode? why?
gold and platinum because they are unreactive
what do you call it when iron and steel corrode?
rusting
what type of reaction is rusting?
redox
what happens to iron when it rusts?
it is oxidised to hydrated iron(III) oxide when it reacts with oxygen and water
what is the equation for rusting?
iron + oxygen + water -> hydrated iron (III) oxygen
what does hydrates iron (III) oxide look like?
orange brown rust that flakes off the surface of an object leaving fresh metal underneath and can continues until an object has completely corroded away
name four mathods of preventing/ reducing rusting
1) paining
2) coating with oil/grease/plastic
3) galvanising (plating with zinc)
4) plating with tin
what are the issues with using paint/oil/grease to protect metals from rusting?
if the paint is damaged rusting starts on the exposed metal and continues underneath until it flakes of exposing fresh metal to air/water
what is sacrificial protection?
rust prevention where a more reactive metal than iron such as magnesium or zinc corrodes in preference to iron/steel so the more reactive metal corrodes first
when is sacraficial protection used?
when painting is difficult eg on ship hulls where they have zinc/magnesium blocks bolted onto their hulls below the waterline
what is a problem with using sacrificial corrosion on boats hulls?
they gradually ccorrode away and have to be replaced
what is the half equation for iron (III) in rusting?
Fe -> Fe 3+ + 3e-
what is the rule for reactivity of ametal in terms of electrons?
the more reactive a metal is the easier it looses its electrons
what is metal plating?
where a layer of metal is plated onto a iron or steel metal object preventing air and water form reaching the iron/steel below
what si galvanising?
coating iron/steel with a thin layer of zinc
what two things does the thin layer of zinc from galvanising do after it has cooled?
1) it stops air and water reaching the iron/steel below
2) it acts as a sacrificial metal so that the object is protected even if the zinc layer is damaged
what are the two ways in wich you can plate a metal with tin?
1) electroplating the steel object with tin
2) dipping the object in molten tin
what is an issue with tin plating?
tin is less reactive than iron and if the tin layer is damaged the steel acts as a sacrificial metal for the tin so rusts faster than normal
what are ceramics?
hard non metallic materials
give 4 examples of ceramic materials
1)brick
2)china
3)porcelain
4)
what are ceramics made from? what is their structure like?
contain metals and non - metals combined to form giant ionic lattices or giant covalent structures
what are the typical properties of ceramc?
1) high melting points
2) hard stiff and brittle
3) poor conductors of electricity and heat
why are most ceramics unreactive?
their compounds are mostly oxides
how is glass produced?
by melting sand and them allowing it to cool and solidify
what are the properties of glass?
1) irregular giant structure
2) no crystals
3) transparent
how are most ceramics made?
by heating clay to high temperatures causing tiny crystals form joined together by glass
what is china/ porcelain usually coated in and why?
usually coated in a glaze and reheated forming a smooth hard waterproof surface
what are the 4 desired qualities you want when choosing the material for a metal cable
1) good conductor of electricity
2) lightweight
3) strong so it doesn’t stretch or snap easily
4) resist corrosion
what three metals could be considered for use in eletrical cables?
aluminium, copper and steel
why is aluminium chosen for overhead electricity? (in comparison to steel)
it is a good conductor and less dense than steel but not as strong
why is copper chosen for electrical wires in comparison to steel and aluminium?
it is the best conductor of electricity but has a low tensile strength and the highest density meaning it will be heavy
what must insulators do?
prevent energy from escaping
what is poly(propene)? what are its properties? (in comparison to glass and porcelain)
it is a tough flexible polymer with the poorest electrical resistance and its tensile strength is the lowest so would snap easily when stretched and has the lowest comprehensive strength so would squash easily
what is compressive strength?
the measure of how strong a material is when squashed
what are the properties of porcelain (in comparison to glass and poly(propene)?
lower resistance than glass but higher compressive strength
what would be the most suitable insulator for where cables are fixed to the top of a structure
porcelain
what is a composite material?
a material made from two or more materials combined together and each has different properties making te properties of the composite material different to that of the materials it contains
name 3 ways in which a composite material may be different to the materials it contains
1) stronger
2) less dense
3) cheaper than separate components alone
name 3 properties of cotton fabric
1) lightweight
2) comfortable
3) not hard wearing
what is polyester cotton?
a composite material made by weaving cotton thread ith polyester fibre and artificial polymer
what are the properties of polyester-cotton?
comfortables, hardwearing and easy to wash/dry
what is resin?
a substance that changes from the liquid state to the solid state because of chemical reactions
what fibres do many polymer materials consist of?
fibres embedded in polymer resin
what is the difference between polymer fibres and polymer resin?
polymer fibres have a low density but high tensile strength but are brittle while resin is hardwearing but not strong
what are the properties of the composite material created by combining polymer fibres and resin togtether?
lightweigh, strong and hard material
what does fibreglass contain?
glass fibres in a resin
what is fibreglass used for?
canoes, boats and surfboards
what is carbon fibre made of?
carbon fibres in a resin
what is carbon fibre used for?
racing cars and aircraft parts as it is more expensive than fibreglass
what is concrete?
a composite material made up of aggregate(small stones), sand and cement
what happens when water is added to concrete?
chemical reactions happen binding he ingredients of the concrete together
what is the compressive strength of concrete? what does this make it useful for?
high compressive strength making it useful for building foundations
