ID and gases Flashcards
ammonia test
damp UI / red litmus paper
goes blue
CO2 gas test
limewater
goes cloudy
Cl2 gas test
damp UI/blue litmus paper
goes red then beaches
CO2 test - equation
Ca(OH)2 (aq) + CO2(g) > CaCO3(s) + H2O(l)
Cl2 test equations
Cl2(g) + H2O(l) > HCl + HOCl
H2 gas test
lit splint
squeaky pop
H2 gas equation
2H2 + O2 > 2H2O
O2 gas test
glowing splint
relights
water vapour test
anyhdrous copper sulphate (white)
goes blue
carbonate ions test
+acid - effervescence
bubble through limewater - clear>cloudy (proves CO2 made)
carbonate ions - equation
2H,+(aq) + CO3,2-(aq) > H2O(l) + CO2(g)
sulphate ions test
add acid eg HCl (to remove carbonate ions and wont interfere with BaCl2)
add anything with barium ions in eg BaCl2 - white ppt.
sulphate ions test equation
SO4,2-(aq) + Ba,2+(aq) > BaSO4(s)
halide ions test
add HNO3 (remove carbonate ions, wont interfere as has nitrate ions in)
add AgNO3
result
- Cl2 - white
- Br2 - creme
- I2 - yellow
halide ions test equation eg Br2
Br,-(aq) + Ag,+(aq) > AgBr(s)
flame test method
- dip nichrome wire into HCl(aq) + heat in roaring flame to clean wire
- dip wire back into HCl and into the test substance so it sticks to wire
- put wire in the roaring flame and observe the colour
sodium flame colour
orange
lithium flame colour
crimson
potassium flame colour
lilac
calcium flame colour
brick red
copper flame colour
blue-green
magnesium flame colour
none
copper ion test
add NaOH
goes blue
iron(II) ion test
add NaOH
goes green
iron(III) ion test
add NaOH
goes red-brown
why does iron(II) hydroxide ppt. darken on standing
oxidises in air
ammonium ion test
- add sodium hydroxide
- heat gently
- test gas with damp UI paper(goes blue) as ammonia is evolved
ammonium ion test equation
NH4,+(aq) + OH,-(aq) > NH3(g) + H2O(l)
pure water test
exact boiling point 100C
composition of air
N2 - 78%
O2 - 21%
other gases - Ar(0.9%) CO2(0.035%) water vapour/noble gases(0.065%)
finding % of oxygen in air
- copper + oxygen react
- iron fillings rust
- add phosphorous
finding % of oxygen in air - copper and oxygen react
- 100ml gas passed over excess fine copper pieces (large SA to react + Cu isn’t limiting)
- heated
- as O2 reacts with Cu amount reduces
- when no more change in volume stop heat
- left to cool (gas un-expands back to normal)
- measure volume at end and calculate vol of O2 present and %in air
finding % of oxygen in air - iron filing rust
- iron fillings held onto inside of boiling tube with vaseline
- put upside down in a water bath
- water level rises as vol of gas decreases as it reacts with iron so water takes gases place
- water level rises to constant level once all O2 has reacted
(use measuring cylinder to measure volume of air at start/end and find % of O2 in air)
finding % of oxygen in air - phosphorus
P4 + 5O2 > P4O10
similar to iron as it burns and reacts water level rises
phosphorus goes out when all O2 has reacted
use % change of volume = % of O2 reacted (%of O2 in air)
CO2 uses
- make fizzy drinks - slightly soluble in H2O to form carbonic acid
- fire extinguisher - denser than air - smothers O2
- dry ice
- packaging to stop oxidation - inert
make CO2
react carbonates + acid
- CaCO3(s) + 2HCl(aq) > CaCl2(aq) + H2O(l) + CO2(g)
- speed up - heat, mix, smaller pieces of reactant, higher concentration of HCl
thermal decomposition of metal carbonate
- heat copper carbonate - green>black
CO2 as a greenhouse gas
can absorb infrared radiation radiated from Earth
increased CO2 traps more heat (leading to global warming)
thermal decomposition to copper carbonate
CuCO3(s)>(heat)> CuO(s) +CO2(g)
- green > black
CO2 - pollutant
formed
- respiration
- combustion of fossil fuels
- organic decomposition
greenhouse gas
- more CO2 leads to global warming
solution
- reduce CO2 in sky - plant trees - conserve forests(remove CO2 by photosynthesis) - capture CO2 from plants/factories
CO - pollutant
formed
- incomplete combustion of fossil fuels
TOXIC
- combines with haemoglobin so blood carries less O2
solutions
- clean heating systems (prevent soot build up) -ensure complete combustion
- CO detector
Sulphur dioxide - pollutant
formed
- burning fossil fuels (coal)
acid rain
- kills plants/ acidifies lakes
- weathers limestone/ erodes building
solutions
- wash coal to remove sulphur before burning
- use less sulphur coals
- scrubbers remove SO2
nitrogen oxides - pollutant
formed
- combustion - when fossil fuels burn
- oxidations of N2 in engines
- lung disease (asthma)
- acid rain - harm vegitation
- photochemical smog
solutions
- use less nitrogen fertiliser
- use low nitrogen burners
- catalytic converters
burning metals
form basic oxides
turn UI blue
burning non-metals
form acidic oxides
1dm^3 to cm^3
1000cm^3
molar gas volume at room temp and atmospheric pressure
24 dm^3/mol
moles (gases)
n = volume (dm^3)/ 24
moles solids
n = mass(g) / Mr
moles (solutions)
n = volume (dm^3) X concentration (moldm^-3)
