Studied by 6 people
What are the ‘Alkali metals’ (group 1)?
lithium, sodium, potassium, rubidium, caesium and francium
What are the physical properties of the Alkali metals?
low melting points, low density, very soft
What form of bonds do alkali metals form?
ionic compounds (lose one outer electron easily)
What is the pattern of reactivity in alkali metals?
they become more reactive as you go down the group
How do alkali metals react with water?
they react vigorously and produce hydrogen gas and a hydroxide of the metal
What are the group 7 elements (halogens)?
fluorine, chlorine, bromine, iodine and astatine
What are the properties of group 7 elements?
diatomic molecules and increasing melting and boiling points down the group
What are the elements like at room temperature?
Chlorine - green gas
Bromine - red-brown liquid with an orange vapour
Iodine - dark grey crystalline solid with a purple vapour
What is the pattern on reactivity in group 7?
the elements become less reactive down the group
What is formed when halogens and alkali metals react?
salts called metal halides
What is a displacement reaction?
when a more reactive element displaces a less reactive element from a compound
What are the group 0 elements (noble gases)?
helium, neon, argon, krypton, xenon and radon
What is the property of noble gases at room temperature?
colourless gas and monatomic (single atoms)
Why are noble gases inert?
they have full outer shells and are non-flammable
What are the patterns of the properties of noble gases?
the boiling, melting and density increase down the group
What are three examples of the transition metals?
copper, iron and zinc
What are the typical metallic properties of transition metals?
they are hard, strong, shiny and conduct heat and electricity with high melting points and densities
What is an example of a transition metal being used as a catalyst?
iron is used in the haber process for making ammonia
What is an example of transition metals ions?
copper has Cu+ and Cu2+
What does metals reaction with acids mean for reactivity?
if a metal loses its outer electron to form a positive ion is it more reactive
What does metals reaction with water mean for reactivity?
very reactive metals react vigorously
What safety precautions are needed for tests of gases?
tested in a fume cupboard
What is the test for carbon dioxide?
bubbling it through lime water - turning cloudy if co2 is present
What is the test for hydrogen?
makes a squeaky pop with a lightened splint
What is the test for chlorine?
damp blue litmus paper will be bleached white
What is the test for halide ions?
dilute nitric acid with a few drops of silver nitrate solution
chloride - white
bromide - cream
iodide - yellow
What is the test for carbonates?
barium chloride solution produce a white precipitate add hydrochloric acid will fizz
What is the test for sulfate ions?
barium chloride solution produce a white precipitate add dilute hydrochloric acid will not dissolve
What are the flame results for metal ions?
lithium - red
sodium - yellow
potassium - lilac
calcium - brick red
copper - blue-green
What metal ions form colour precipitates with sodium hydroxide?
calcium - white
copper - blue
iron(II) - green
iron(III) - brown
zinc - white then colourless
What are the advantages of instrumental methods?
sensitive, fast and accurate
What are the different ways machines are used to analyse samples?
infrared spectroscopy, ultraviolet spectroscopy, gas chromatography and mass spectroscopy
What is concentration?
the more solute you dissolve in a given volume the more crowded the molecules are and the more concentrated the solution is
How do you work out concentration?
mass of solute / volume of solution
What is a standard solution?
any solution that you know the concentration of
What is a titration?
allow you to find out exactly how much acid is needed to neutralise a given quantity of alkali
How do you do a titration?
1 - use a pipette to measure a volume of alkali and add a few drops of indicator
2 - fill a burette with acid and slowly ass it to the alkali
3 - swirl the flask and record the volume of acid used to change the solutions colour
How do you work out concentration using titration results?
number of moles / volume of solution
What is a molar volume?
the volume occupied by one mole of a gas
What is the formula for molar volume?
gas volume / number of moles
What is the formula of molar volume when under the same conditions?
volume = moles x 24
What is percentage yield?
the percentage of product you get from a reaction
How do you work out the percentage yield?
actual yield / theoretical yield x 100
What is atom economy?
the percentage of the mass of the reactants that has been converted into your desired product
What is the formula for working out the atom economy?
total m of desired products / total m of all products x 100
Why is high atom economies better?
high atom economy use up resources slowly and make less waste meaning sustainable and profitable reactions
What is the rate of reaction?
how quickly a reaction happens
What is the formula for the rate of reaction?
amount of reactant used or amount of product formed / time
What is the rate of reaction experiment involving precipitation?
mixing too see-through solutions produces a precipitate which clouds the solution (experiment by using a piece of paper with a mark and observing the time for the mark to become obscured)
What is the rate of reaction experiment involving change in mass?
use a mass balance to measure the production of gas the quicker the reading on the balance drops - the faster the reaction
What is the rate of reaction experiment involving volume of gas?
use a gas syringe to measure the volume of gas given off, the more gas given off during a time interval - faster the reaction
How do you work out the gradient?
change in y / change in x
What is the collision theory?
the more successful collisions there are the faster the reaction is (higher rate of reaction)
What three factors increase the rate of reaction?
increasing temperature
increasing concentration
more surface area
What is a catalyst?
a substance that increases the rate of reaction without being chemically changed
How do you identify a catalyst in chemical reaction?
measure the reaction rate with x and then without but instead with a known mass if the rate increases and x is unchanged then it is a catalyst
How do enzymes control cell reactions?
enzymes speed up chemical reactions in living cells eg. respiration
What is a reversible reaction?
the products can react with each other to produce the original reactants
How do reversible reactions reach equilibrium?
after while the foward reaction will be going at exactly the same rate as the backward one
What is the position of equilibrium?
the position can be on the right or the left depending on the conditions
What are the three factors that change the position of equilibrium?
temperature, pressure and concentration
What is Le Chatelier’s Principle?
states that if there is a change in concentration, pressure or temperature in a reversible reaction the position will move
How does temperature affect the position of equilibrium?
decrease - move to the exothermic direction
increase - move to the endothermic direction
How does pressure affect the position of equilibrium?
increase - move towards the side with fewer moles of gas
decrease - move towards the side with more moles of gas
How can you predict how the position of equilibrium will change?
changing conditions
Why is extracting metal from ores worthwhile?
a metal ore is a rock which contains enough metal to make it economically worthwhile
How is metal extracted from ores?
extracted from res chemically by reduction or electrolysis
How are metals extracted using reduction with carbon?
when an ore is reduced, oxygen is removed from it - the position of the metal in the reactivity series determines whether it can be extracted by reduction
What metals have to be extracted by electrolysis?
metals that are more reactive than carbon
Why is copper purified by electrolysis?
the copper produced is very pure and is a better conductor
What is biobleaching?
bacteria gets energy from the bonds between atoms in the ore separating out the metal in the process
What is phytoextraction?
growing plants in soil containing metal compounds which builds up in the leaves, the plant is then harvested dried and burned to collect the compounds
What is an alloy?
mixture of two different metals or a metal and a non-metal
What is steel and alloy of and what are its properties?
iron and carbon - harder, stronger and less likely to rust
What is brass and alloy of and what are its properties?
copper and zinc - harder and used for musical instruments
What is bronze and alloy of and what are its properties?
copper and tin - resistant to corrosion and used for sculptures
What is solder and alloy of and what are its properties?
lead and tin - low melting point and is used to connect components
What is duralumin and alloy of and what are its properties?
aluminium, copper and magnesium - low density and used for aircraft
What type of reaction is the rusting of iron?
redox as iron losses electrons in the presence of oxygen
How to prevent corrosion?
painting, oiling and coating
How does coating in tin protect steel from corrosion?
the tin acts as a barrier stopping water and oxygen from reaching the surface of metal
How do reactive metals prevent corrosion?
the water or oxygen reacts with the more reactive ‘sacrificial’ metal instead of the other metal
What is galvanising?
a coat of zinc is put onto iron as it is more reactive and will lose electrons in preference to iron
What is needed to make ammonia?
nitrogen obtained from the air and hydrogen obtained from hydrocarbons in a reversible reaction
What are the reaction conditions for the haber process?
is a compromise - 200 atm to favour the foward reaction without being too expensive, 450c as the foward reaction is exothermic without temperature being too low that it slows the rate of reaction
Why is an iron catalyst used in the haber process?
makes the reaction go faster without affecting the position of equilibrium
How do fertilisers help plants grow?
they contain three essential elements (nitrogen, phosphorus and potassium)
How is ammonia produced into a fertiliser?
ammonia is a base and can be neutralised by acids to make ammonium salts using nitric, sulfuric, phosphoric acid
How is ammonium sulfate prepared in a lab?
titration - adding sulfuric acid to ammonia (methyl orange indicator) then without indicator for pure crystals
What is the contact process?
burning sulfur in air to make sulfur dioxide then oxidising this to make sulfur trioxide, which is used to make sulfuric acid
What are the conditions in the contact process?
temperature - 450c exothermic
pressure - increase in pressure to shift the equilibrium to the right
catalyst - vanadium pentoxide
What must be considered when designing industrial processes?
cost of raw materials - refining and extraction costs
availability of raw materials - non-renewable materials will run out
energy costs - reaching and maintaining conditions
rate - optimum conditions
equilibrium position - if position lies to the left then there will be a low yield
What are the four stages of a life cycle assessment?
materials and manufacturing, transport, product use, disposal
What does extracting raw materials require?
takes large amounts of energy from burning fossil fuels (which are running out)
How does the recycling process work?
energy is needed to reprocess materials into new forms however it can be expensive and the product is of a lower quality
What are polymers and what are there properties?
the reaction of different monomers - strong, stretchy and easily moulded (water pipes)
What are ceramics and what are there properties?
baking substances like clay - brittle and stiff
How is pottery and bricks formed?
clay is formed from weathered and decomposed rock, it is easily moulded and then fired at a high temperature
How is most glass formed?
heating limestone, sand and sodium carbonate to make soda-lime glass (transparent and strong)
What is a composite? (+example)
one material embedded in another - fibreglass has a low density but is strong and used for boats
Note 
Flashcard (29)