Topic 4 / 5 Flashcards
reactivity series mnemonic
please stop calling me a careless zebra instead try learning how copper saves gold
reactivity series
potassium sodium calcium magnesium aluminium carbon zinc iron tin lead hydrogen copper silver gold
more reactive metals
have a greater tendency to lose electrons and form positive ions
silver gold and platinum
found underground as uncombines metals as they are unreactive so don’t chemically join with any element to form a compound
phytoextraction
+ metals can be extracted from contaminated soils
- weather dependant
- requires high temperatures (burning)
- more expensive than mining ores
BIOLEACHING
+ doesn’t require high temperatures
- releases harmful gases like sulfur dioxide which damages the environment
both p and b
- very slow process
+ preserves supplies of higher grade ores
+ less damage to environment
rusting is a _________ reaction
oxidation reaction
redox reactions
oxidation and reduction happen simultaneously
e.g. displacement reactions
extracted by heating with carbon
metals less reactive tha corbon
extracted by electrolysis
above carbon
making copper
- place copper oxide and carbon powder into a crucible
- put thin layer of carbon powder to ensure all the copper oxide reacts
- place the lid
- heat crucible strongly
- solid copper produced
cryolite
an aluminium cmpound with a much lower melting point than aluminium oxide so using this reduces the cost of extracting
economic advangates of recycling
less energy needed so lower lost than mining
enviromental advantages
natural reserves of metal ores will last longer
produces less pollution
less metls end up in landfill
doesn’t ruin habitats
less noise and dust
advantages of recycling
- cheaper because no need to pay for electricity
- less air pollution eg sulfr dioxide
- doesn’t ruin teh environment habitats
- requires less energy than extracting eb electricity is needed to extract aluminium
- landfill sites don’t get full
- reduces need to mine ores so don’t run out
transition metals
high melting and boiling point
high density - metal cations are densely packed together
conducts heat
conducts heat
malleable
ductile
colourful
can act as catalysts in different reactions
copper
blue
nickel
green
cobalt
pink
iron
yellow
harbour process to make ammonia
iron catalyst
catalytic converter in cars
platinum converter
rust…
a metal oxide layer that forms on the outside of the metal
we can prevent rusting by
- excluding oxygen
- excluding water
- sacrificial protection (galvanising)
- electroplating
sacrificail protection
a method that doesn’t rely on excluding oxygen or water
instead, a piece of zinc or magnesium is attached to the iron or steel
will oxideise more easily so reacts with them instead of the iron/ steel object
this protection continues until the sacrificial method corrodes away
electroplating
coating a metal with another metal for protective or aesthetic reasons
uses electrolysis to transfer the metal atoms onto the surface of teh other metal
why are some objects electroplated
- aesthetics e.g. shiny
- to prevent corrosion as it wont react with oxygen or water
silver ring
silver atoms lose electrons and become silver ions
silver ions go into electrolyte and move to negiv=tavely charged copper ring
silver ions gain electrons and left as silver atoms
alloy
a mixture of one or more metal element, mostly metal
irregular arrangement in layers so less malleable and atoms arent able to easily slide over each other
pure metals
regular layers of metal ions, layers can easily slide over each other
cartas
mass of pure gold/ 24 parts of the alloy
alloy proteries
- decreases malleability
- increases hardness
- increases corrosion resistance
wedding ring
platinum used which is expensive and unreactive will stay shiny
concentration in g dm-3
mass of solte / volume of solution
concentration in mols
concentration g dm-3 / ram
titration accuracy
- use an indicator so we see the end point of teh reaction by a colour change
- glass pipette to maintain an accurate volume
- read from bottom of miniskus
- use a white tile to more easily see the colour change
- add solution drop by drop near the end point to identify exactly when teh colour changes
- make sure there are no bubbles in teh burrito / pipette
- consistintky SWIRL teh flask to ensure mixing of alkali and acid
- wash pipette to avoid contamination
chemical and fuel cells
- two different metals can undergo a redox reaction if they are in contact with salt solution of therir own metal
- greater different in reactivity between teh two metal teh higher the voltage produced
- the curicit must be completed with a salt bridge which allows ions to flow from one half of the cell to the other chemical cells
the daniel cells
alkaline batteries
non rechange
what happens when one of the reactants run out batteries
modern batteries contain solution mixed with a powder to form a paste
we call the call these dry cells
hydrogen fuel vs petrol
+ only water product is H2O non-pollution
+ 40-60% efficient
+ requires less maintenance
+ oxygen readily available
+ doesn’t produce CO2
- expensive to make
- slightly flammable so have to be stored carefully
- few rechargeable stations
- hydrogen not easily purchased
- heavy and costly to transport
petrol/ disel
+ easier to store, many filling stations
- noisy in use, CO2 waste product, many moving parts
iron + water + oxygen
hydrated iron oxide
Explain why iron rod rather than stainless steel rod is used in this experiment.
they would take too long to corrode as stainless steel is more resistant to corrosion, doesn’t react with water/ oxygen
actual yield
yeild made in a reaction
theoretical yeild
maximum yield calculated using the balanced equation with no losses
State two reasons why the actual yield of a reaction is usually less than the
theoretical yield
- side reactions
- some reactants remained unreacted
Adding catalyst
rate of attainment increases
yeild attained stays the same
Explain what effect a pressure higher than 200 atmospheres would have on the rate of
attainment of equilibrium and on the equilibrium yield of ammonia.
- equilibrium shifts to the right
- rate of attainment is quicker
- yeild increases
- moves to fewer molecules
Stage 1 takes in heat energy, it is endothermic.
Explain the effect of increasing the temperature on the yield of the products of stage 1.
equilibrium shifts to the right
higher yeild
The overall equation for the process is
0.40 g of methane were fully reacted with steam to form carbon dioxide and hydrogen.
Calculate the maximum volume of hydrogen in dm3
, measured at room temperature and
pressure, that could be made in this reaction.
(relative formula mass: CH4 = 16, 1 mol of any gas at room temperature and pressure
occupies 24 dm3
)
2.4
Explain what is meant by a dynamic equilibrium
rate of foward and backward reactions is the same with no overall change (no chnage in volume)
increasing concentartion
equilibrium reached faster
When there are alternative methods of producing a product, the final pathway is
chosen by considering atom economy, cost of energy, yield of product and rates
of reactions.
State another factor that should also be considered.
equilibrium position/usefulness of by-products
What is the source of the hydrogen used in the Haber process?
natural gas
Explain why the amount of ammonia remains constant.
forward and back reactions take
place / reversible / dynamic (1)
at the same rate / equilibrium (1)
The voltage of a cell is 1.5 V.
Give a reason why this voltage of the cell decreases when the cell is left connected in a
circuit.
reactants are used up
Give one advantage of using a hydrogen-oxygen fuel cell, rather than using a chemical cell,
to power a vehicle.
constant voltage as long as reactants provided
Explain what is meant by a dynamic equilibrium.Explain what is meant by a dynamic equilibrium.
