Topic 3 Flashcards
sulfuric acid
H2SO4
Hydrochloric acid
HCl
Nitric acid
HNO3
Sodium Hydroxide
NaOH
Potassium Oxide
K2O
Ammonium hydroxide
NH4OH
neuteral
7
acidic
1-6
alkaline
8-14
alkali properties
- slippery
- soapy
- burns
- corossive
e.g. bleach
acid properties
- sour
- corrosive
e.g. lemon juice
universal indicator
acid : red, orange, yellow
alkali : blue, purple
Methyle orange
acid: red
alkaline: yellow
phenophelin
acid: colourless
alkaline: pink
litmus paper
acid: blue to red
alkaline: red to blue
whats the best indicator
ph pro/ metre as it doenst ruin the solution and tells you how strong or weak the substance is
hydrogen ion
H+
Hydroxide ion
OH-
Nitrate
NO3 -
hydroxide
OH -
Carbonate
CO3 2-
Sulfate
SO4 2-
acids are
chemicals that when dissolve split to release hydrogen ions
alkalis are
bases that when dissolved in water split to release hydroxide ions
neuteral solutions
have an equal amount of H+ and OH- ions
strong acid
completely dissociated into H+ ions
weak acid
partially dissociated into H+ ions
ph scale measured by
how many H+ ions there are
ph scale H+ ions
PH 2 has ten times more H+ ions than PH 3
all alkalines…
alkalies are bases and are soluble in water
acids are always
aq
H+ + OH-
H2O
hydrochloric acid
chloride
sulfuric acid
sulfate
nitric acid
nitrate
metal oxide + acid
salt + water
metal hydroxide + acid
salt + water
metal + aicd
salt + hydrogen
metal carbonate + acid
carbon dioxide
water
salt
test for hydrogen
lit splint squeaky pop
test for oxygen
glowing splint relights
test for chlorine
blue litmus paper turns red then bleaches
test for co2
blow into colourless limewater
turns cloudy/ milky
solubility nitrates
all soluble
solubility chlorides
all soluble apart from silver and lead
solubility sulfates
all soluble apart from lead, barium and calcium
carbonates and hydroxides
all insoluble except those of sodium potassium and ammonium
precipitation reaction
when an insoluble solid is formed when two soluble substances react
making copper sulfate
1 add excess copper oxide
2 gently warm mixture to speed up the reaction
3 filter to remove unreacted solid from solution
4 heat to evaporate water and concentrate the salt solution
5 leave to evaporate water slowly for crystallisation to occur
Copper ions produce
clear blue solution
Titration
- mesure teh alkali using a pipette
- add a few drops of indicator phenothiazine
- add acid from teh burette
- continue adding acid until there’s a colour change and end point recorded
- repeat without indicator
- add salt solution to evaporating dish and heat until the water has evaporated to concentrate
- leave dish in warm place like a radiator to allow water to vaporise and crystals to form
acid + base
add an excess of the insoluble base to use up all the acid
filter off the left over base
acid + alkali
mix the acid and alkali until the soloution is neuteral ensureing no left over acid or alkiali
check ph7
anhydrous salt crystals
no water in them
boil off all the water
hydratyed slat crytsals
have water in them
boil off some of the after and leave it to evaporate and crystalise
electricity is needed to
needed to break down ionic compounds
negative eletrode
cathode
cations
positive eletrode
anode
anions - halogens
AlO
cathode: aluminium
anode: oxygen
potassium Iodide
cathode: potassium
anode: iodine
electrolysis of zinc chloride
zinc ions gain 2 electrons to become zinc atoms
each chloride atom looses one electron to become chloride atom
2 chlorine atoms bond to form a molecule
at the cathode
if the metal is more reactive than hydrogen, hydrogen will be produced
at the anode
if halogen is present it will form
if not present OH- will form
pure copper cathode
gains mass
impurites
from the anode dont form ions and collect bellow as sludge which is collected as it may conatin valuable metalic elements
impure copper anode
coppper atoms loose two electrons to become copper ions
loose mass
these ions dissolve into teh solution and migrate to the pure copper cathode where they gain electrons to become copper atoms
looses mass
unreactive
inert
equation at the anode
Cu -> Cu 2+ + 2e-
at the cathode
Cu2+ + 2e- -> Cu
acid reacts with alkali
neutralisation
how is h2 gas produced at teh cathode
H+ ions are attracted to the cathode , gain electrons and form hydrogen gas.
how is O2 gas produced at teh anode
OH - ions are attracted to the anode , lose electrons and form oxygen gas.
why does teh solution remain blue
the same amount of ions entered and left the solution
Suggest why universal indicator must not be used in titration experiments
colour chge too gradual, too many colours
Explain, in terms of the particles present, why the pH increases during the experiment.
H+ ions neuteralised
H+ +OH- -> H2O
less H+ ions, concentration falls
) State two observations that would show the reaction has finished.
no more colour chnage
bubles stop
Suggest a reason why the actual yield was greater than the theoretical yield
not all the water had evaporated