inorganic chemistry: gases in the atmosphere

percentages of 4 most common gases

nitrogen - 78%

oxygen - 21%

argon - 0.96%

co2 - 0.04%

draw phosphorus oxygen experiment

check notes

need: bell jar + bung, trough of water, evaporating/ceramic dish, phosphorus

why use phosphorus?

it reacts readily with oxygen until it is all used up, burns

iron wool version (find oxygen percentage) (3)

1. soak iron wool in acetic acid to catalyse reaction

2. push iron into end of boiling rube, turn upside down, put in water

3. record origin water level, wait 7 days, record new water level

iron wool oxygen results explained

iron reacts with oxygen in air (iron oxide/rust), water rises to fill space left

volume change = volume of oxygen??

copper syringes experiment steps (4)

1. put copper turnings in a tube and attach glass syringes to either end (one full of air, the other empty)

2. heat copper with busen burner; push air back/forth over copper turnings

3. as copper and oxygen react, the overall volume of air will decrease

4. push all air into one syringe and calculate final volume

how to calculate percentage of O2 in air (copper syringes)

difference in volume (start vol - final vol) / start vol (x100%)

should be around 21%

define combustion

burning, with oxygen

is combustion exo/endo thermic

EXOthermic

	Magnesium	Hydrogen	Sulfur
Observations		+flame colour
Equation

	Magnesium	Hydrogen	Sulfur
Observations	bright white light, white powder produced	orange flame, water produced (squeaky pop test is mini explosion)	pale blue flame, pungent/(colourless) gas produced
Equation	2Mg (s) + O2 (g) → MgO (s)	2H2(g) + O2 (g) → 2H2O (g)	S (s) + O2 (g) → SO2 (g)

MgO pH dissolved in water

MgO is alkaline /basic in water

SO2 pH dissolved in water

SO2 is acidic in water

define thermal decomposition

the breaking down of a compound using heat

general thermal decomposition formula for metal carbonate

metal carbonate → carbon dioxide + metal oxide

copper carbonate colours vs copper oxide colour

copper carbonate - green

copper oxide - black

both powders

earth’s temperature is a balance between the ____ it gets from ___ _____ and the ___ it _____ _____ out

earth’s temperature is a balance between the HEAT it gets from THE SUN and the HEAT it RADIATES BACK out

copper carbonate equation

copper carbonate → copper oxide + CO2

CuCO 3 ( s ) → CuO ( s ) + CO 2 ( g )

main 3 greenhouse gases

methane (CH4), CO2, water vapour

explain the greenhouse effect (succinct)

greenhouse gases trap heat in the atmosphere by absorbing and re-emitting the radiation reflected out from the Earth’s surface