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Chemistry

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102 Terms

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universal indicator alkali
blue/purple
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universal indicator acid
red
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element which forms a basic oxide
copper
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bromine at room temp
red-brown liquid
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chlorine at room temp
yellow-green gas
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iodine at room temp
grey solid
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rf equation
distance moved by substance/distance moved by solvent
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obtain pure dry crystals from salt solution
heat to evaporate water,

leave to cool,

filter to obtain crystals,

leave to dry (oven)
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diamond electricity
does not conduct electricity as no free electrons
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diamond melting point
very high as strong covalent bonds in rigid structure
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diamond uses
cutting tools as very hard
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graphite electricity
conducts electricity as contains delocalised electrons free to move
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graphite melting point
high as contains lots of strong covalent bonds
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graphite uses
lubricant as layers can slide over each other
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diamond and graphite structure
giant covalent structures
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diamond structure
tetrahedral
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graphite structure
hexagonal
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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
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forces of attraction in covalent bond
sharing of electrons between two attracted nuclei
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half equation for formation of oxygen during electrolysis
4OH- = O2 + 2H2O + 4e
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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
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why metals are malleable
layers of atoms which can slider over eachother
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what happens at anode
oxidation, loss of electrons
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what happens at cathode
reduction, gain of electrons
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percantage change
change/original x 100
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why use powder
larger surface area so reacts quicker
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why is argon unreactive
full outer shell so doesnt lose or gain electrons
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percentage of oxygen in air
21%
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what forms acid rain
nitrogen dixoide and water (nitric acid), or sulfur dioxide and water (sulfuric acid)
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magnesium and oxygen observation
bright white flame, formation of white powder
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test for carbon dioxide
bubble through limewater and turns cloudy
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variables to be controlled
concentration of acid, surface area of metal, temperature, volume of acid,
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percentage of nitrogen in air
78%
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percentage of argon in air
1%
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percentage of carbon dioxide in air
0\.04%
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colour of methyl orange
yellow in alkali, red in acid
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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
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phenolphthalein colours
colourless in acid, pink in alkali
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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
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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
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why is soot formed
incomplete combustion due to limited oxygen supply
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soot name
carbon
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heat energy equation
q x c x temp change
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why is volume collected less than expected
gas escaped before bung is placed on flask
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why is measuring cylinder not necessary
acid is in excess so an accurate measurement isnt needed
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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
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pressure increase effect on equilibrium
moves to direction of fewer molecules of gas
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concentration increase effect on equilibrium
moves away from what gained more conc
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temperature increase effect on equilibrium
moves in endothermic direction
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catalyst effect on yield
none as increases rate of both backwards and forwads reaction
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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
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yield change depending on equilibrium
if equilibrium shifts to the right the yield of products will increase
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test for chlorine
damp litmus paper goes from red to white
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test for ammonia
turns red litmus paper blue
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lithium flame test
crimson
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potassium flame test
lilac
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calcium flame test
orange-red
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sodium flame test
yellow
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copper flame test
blue-green
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iron 3 hydroxide colour
brown
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iron 2 hydroxide colour
green
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copper hydroxide colour
green
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test for halides
silver nitrate + nitric acid
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test for sulfates
barium chloride + hydrochloric acid
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positive result for sulfate
white precipitate
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test for water
white copper 2 sulfate turns blue, cobakt 2 chloride strips turn pink
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test for pure water
boils at 100\*C or melts at 0
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products of incomplete combustion of an alkane
carbon monoxide, water
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general formula for alkene
CnH2n
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unsaturated meaning
contains a double bond
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test that a hydrocarbon is unsaturated
add bromine solution and it will turn from orange to colourless
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enthalpy change equation
heat energy/moles
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why crack long chains into short ones
short chains are more useful and have a higher demand
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solid to gas change
sublimation
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test for copper and iron 2
add sodium hydroxide solution, if blue precipitate forms copper is present, if green precipitate forms iron is present
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test for chloride and bromide
add silver nitrate, if white precipitate forms chloride is present, if cream precipitate forms bromide is present
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test to distinguish between alkane and alkene
bromide solution stays orange for alkane, and becomes colourless for alkene
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ionic bond
electrostatic attraction between oppositely charged atoms
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why is it not safe to heat alcohol in an evaporating basin with a bunsen burner
they are flammable
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properties of aluminium
high mp, resistant to corrosion, good conductor of thermal energy
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why is fermentation of ethanol anaerobic
ethanol would react with oxygen to make ethanoic acid
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equation for complete combustion of ethanol in air
C2H5OH + 3O2 = 2CO2 + 3H2O
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conditions for making ethanol with steam
300\*C, 60-70 atm
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dynamic equilibrium
state where a reaction is taking place in both reactions at the same rate at the same time
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mol equation for mol/vol topic
vol/24000cm3
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why is pencil line below water line
so inks dont mix with water
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hydrogen qualities
flammable, low density
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isomer
compound with the same molecular formula but different structural formula
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exothermic energy profile
products below reactants
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bond breaking
endothermic, needs heat energy
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bond making
exothermic, releases heat energy
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problem with disposal of addition polymers
landfill sites getting full, greenhouse gases produced when burned
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lower hydrocarbon qualities in crude oil
darker colour, higher boiling point, high viscosity
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why is carbon monoxide poisonous
reduces capacity of blood to transport oxygen
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complete combustion of hydrocarbon products
carbon dioxide + water
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crude oil fractions top to bottom
gases, petrol, kerosene, diesel oil, fuel oil, bitumen
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crude oil rhyme
good penguins keep diving for bass
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chemical test for water
anhydrous copper sulfate turns from white to blue
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reactivity trend down group 7
gets less reactive as you go down
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combustion of hydrogen in air
2H2 + O2 = 2H2O