separate chemistry Flashcards
what are the typical properties of transition metals
-hard
-strong
-shiny
-conduct heat and electricity
what are alloys
they are made by adding another element to a metal. this can be a metal or a non metal
why are alloys stronger than pure metals
as the other element will stop the layers of the metal from sliding over each other. this means that the alloy is less malleable
how is the alloy steel made
by adding small amounts of carbon to the pure iron
how is the alloy bronze made
copper + tin
what is bronze used for
medals, statues and decorations
how is the alloy brass made
copper+zinc
what is brass used for
water taps and door fittings
how pure is 24 carat gold
100%
how pure is 18 carat gold
75%
what is aluminium alloys used for
to make aircrafts
how is the alloy magnalium made
aluminium+magnesium
what is magnalium used for
make parts for cars and aeroplanes
why do metals corrode
due to the presence of oxygen which causes oxidation
what is rusting
this is the corrosion of iron
what are the 3 ways to prevent rusting
painting
-electroplating
-sacrificial protection
how does painting prevent rusting
it creates a physical barrier between the metal and the air
how does sacrificial protection prevent rusting
this involves placing a more reactive metal with the metal you want to protect. the oxygen will then react with the more reactive metal. however, the more reactive metal will need to be constantly replaced
what is electroplating
coating the surface of a metal with another metal using electrolysis
how do you do electroplating
-your cathode is the object your going to electroplate
-your anode is the bar of metal your using for the plating
-your electrolyte is the solution containing the metal ion of the metal your using for the plating
why are titration experiments used
to find out concentrations of a liquid
what is the formula for concentration
moles/volume
how do you do titration calculations
-find out the moles of the known
-use equation to do mole ratio to find out moles of unknown
then work out the concentration
what is the formula for percentage yeild
actual yeild/ theoretical yield *100
how to do percentage yield calculations
work out no. moles of reactant
-use balance equation to do mole ratio
-work out mass of this using moles
-then find percentage yield
what is atom economy
the percentage of the reactants has been turned into the desired product
what is the formula for atom economy
total mr of desired products/ total mr of all the products *100
what is the chemical equation of the haber process
N2+H2=NH3
what does the haber process produce
ammonia
what are the three main elements in fertilisers that plants need
nitrogen phosphorus and potassium
what is the molar volume
this is the volume occupied by one mole of a gas
what is the formula for molar volume
volume/number of moles
what is avogadros law
one mole of any gas occupies 24dm3 or 24000cm3 at room temperature and pressure
what is a fuel cell
this is a type of chemical cell thats supplied with fuel and oxygen to produce electrical energy
what fuel do hydrogen-oxygen fuel cell use
hydrogen
what is the equation for the hydrogen-oxygen fuel cells
hydrogen+oxygen= water
what are the advantages of hydrogen-oxygen fuel cells
no pollutants produced
what are the disadvantages of hydrogen-oxygen fuel cells
-needs lots of space to store
-it is explosive so it is also difficult to store
