universal indicator alkali
blue/purple
universal indicator acid
red
element which forms a basic oxide
copper
bromine at room temp
red-brown liquid
chlorine at room temp
yellow-green gas
iodine at room temp
grey solid
rf equation
distance moved by substance/distance moved by solvent
obtain pure dry crystals from salt solution
heat to evaporate water,
leave to cool,
filter to obtain crystals,
leave to dry (oven)
diamond electricity
does not conduct electricity as no free electrons
diamond melting point
very high as strong covalent bonds in rigid structure
diamond uses
cutting tools as very hard
graphite electricity
conducts electricity as contains delocalised electrons free to move
graphite melting point
high as contains lots of strong covalent bonds
graphite uses
lubricant as layers can slide over each other
diamond and graphite structure
giant covalent structures
diamond structure
tetrahedral
graphite structure
hexagonal
why ionic compound has high melting point
giant structure, strong electrostatic attraction between oppositely charged ions so large amount of energy needed to break bonds
forces of attraction in covalent bond
sharing of electrons between two attracted nuclei
half equation for formation of oxygen during electrolysis
4OH- = O2 + 2H2O + 4e
why do ionic compounds need to be molten to conduct electrolysis
when solid, ions arent free to flow and conduct charge but when molten are mobile
why metals are malleable
layers of atoms which can slider over eachother
what happens at anode
oxidation, loss of electrons
what happens at cathode
reduction, gain of electrons
percantage change
change/original x 100
why use powder
larger surface area so reacts quicker
why is argon unreactive
full outer shell so doesnt lose or gain electrons
percentage of oxygen in air
21%
what forms acid rain
nitrogen dixoide and water (nitric acid), or sulfur dioxide and water (sulfuric acid)
magnesium and oxygen observation
bright white flame, formation of white powder
test for carbon dioxide
bubble through limewater and turns cloudy
variables to be controlled
concentration of acid, surface area of metal, temperature, volume of acid,
percentage of nitrogen in air
78%
percentage of argon in air
1%
percentage of carbon dioxide in air
0.04%
colour of methyl orange
yellow in alkali, red in acid
method to produce dry crystals of hydrated
add powder to acid until powder is in excess,
filter off excess,
heat to evaporate water,
cool,
filter crystals,
leave in warm place to dry
phenolphthalein colours
colourless in acid, pink in alkali
titration method
use pipette to add 25cm3 of acid to conical flask,
add a few drops of indicator,
add acid to burette and record initial reading,
drop acid into flask and swirl continuously until it changes colour,
take final burette reading and find volume of acid needed by working out the difference,
repeat to get concordant results
why is the reaction exothermic in terms of bonds
more energy is given out when bonds are made than is when taken in when bonds are broken
why is soot formed
incomplete combustion due to limited oxygen supply
soot name
carbon
heat energy equation
q x c x temp change
why is volume collected less than expected
gas escaped before bung is placed on flask
why is measuring cylinder not necessary
acid is in excess so an accurate measurement isnt needed
dynamic equilibrium
position in a reversible reaction where the concentration of reactants and products remain constant and the forward and backward reactions continue to occur
pressure increase effect on equilibrium
moves to direction of fewer molecules of gas
concentration increase effect on equilibrium
moves away from what gained more conc
temperature increase effect on equilibrium
moves in endothermic direction
catalyst effect on yield
none as increases rate of both backwards and forwads reaction
catalyst effect on rate of reaction
provides alternate pathway so lower activation energy needed for reaction to begin, meaning more collisions so speeds up rate of reaction
yield change depending on equilibrium
if equilibrium shifts to the right the yield of products will increase
test for chlorine
damp litmus paper goes from red to white
test for ammonia
turns red litmus paper blue
lithium flame test
crimson
potassium flame test
lilac
calcium flame test
orange-red
sodium flame test
yellow
copper flame test
blue-green
iron 3 hydroxide colour
brown
iron 2 hydroxide colour
green
copper hydroxide colour
green
test for halides
silver nitrate + nitric acid
test for sulfates
barium chloride + hydrochloric acid
positive result for sulfate
white precipitate
test for water
white copper 2 sulfate turns blue, cobakt 2 chloride strips turn pink
test for pure water
boils at 100*C or melts at 0
products of incomplete combustion of an alkane
carbon monoxide, water
general formula for alkene
CnH2n
unsaturated meaning
contains a double bond
test that a hydrocarbon is unsaturated
add bromine solution and it will turn from orange to colourless
enthalpy change equation
heat energy/moles
why crack long chains into short ones
short chains are more useful and have a higher demand
solid to gas change
sublimation
test for copper and iron 2
add sodium hydroxide solution, if blue precipitate forms copper is present, if green precipitate forms iron is present
test for chloride and bromide
add silver nitrate, if white precipitate forms chloride is present, if cream precipitate forms bromide is present
test to distinguish between alkane and alkene
bromide solution stays orange for alkane, and becomes colourless for alkene
ionic bond
electrostatic attraction between oppositely charged atoms
why is it not safe to heat alcohol in an evaporating basin with a bunsen burner
they are flammable
properties of aluminium
high mp, resistant to corrosion, good conductor of thermal energy
why is fermentation of ethanol anaerobic
ethanol would react with oxygen to make ethanoic acid
equation for complete combustion of ethanol in air
C2H5OH + 3O2 = 2CO2 + 3H2O
conditions for making ethanol with steam
300*C, 60-70 atm
dynamic equilibrium
state where a reaction is taking place in both reactions at the same rate at the same time
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