Industrial processes Flashcards
Goals of industrial processes and how they achieve them
make money, Try to make as much product as they can, as fast as possible, Never want to reach equilibrium as it means products stop being produced (constant macroscopic properties)
Haber process equation
N2 (g) + 3H2 (g) <—> 2NH3 (g), Enthalpy: -92KJ (exothermic)
Conditions of the Haber process
Medium temperature (around 500 degrees), Very high pressure (around 350 atmospheres), A porous (increases surface area) iron/ iron oxide catalyst
Steps of the Haber process
Produces of yield of approximately 40%, N2/H2 enters system in 1:3 ratio, Temperature is raised (500 degrees) as the ?heat exchanger passes over the catalyst? which increases the reaction rate, Gasses are further compressed to 350 atmospheres, Resulting gas mixture is cooled to liquify ammonia (removes ammonia from the equilibrium)- ammonia has the highest boiling point, Liquid ammonia is removed, Nitrogen and hydrogen are recycled
Uses of ammonia
Manufacture of nitric acid, 90% of nitric acid is used to produce fertilizer, The remaining 10% is used to manufacture explosives
Stages of the contact process
Sourcing sulfur dioxide, Converting sulfur dioxide to sulfur trioxide, Absorption of sulfur trioxide and conversion to sulfuric acid
Sourcing of sulfur dioxide
Combustion of sulfur recovered from natural gas and crude oil (not used in WA)
S (L) + O2 (g) —> SO2 (g), Change in enthalpy= -297 KJ
From smelting of sulfide ores of copper, zinc, nickel or lead (prevents sulfur dioxide from entering the atmosphere and causing acid rain)
NiS (s) + O2 (g) —> Ni (l) + SO2 (g)
Converting sulfur dioxide to sulfur trioxide
In contact process, the main equilibrium steps occur in the converter where SO2 gas is oxidised to oxygen to form SO3 gas
2 SO2 (g) + O2 (g) <–(V2O5)–> 2 SO3 (g), Change in enthalpy= -197 KJ
Conditions of the contact process
Moderate temperature- each pass over the catalyst, gases are cooled (400 degrees) and recycled which produces a lot of energy allowing for an almost complete conversion, would benefit from high pressure but not cost efficient so 1 atmosphere is used, vanadium oxide is used as a catalyst
Absorption of sulfur trioxide and conversion to sulfuric acid
Sulfur trioxide is absorbed into concentrated sulfuric acid (can’t go in water as so exothermic, it becomes mist), SO3 (g) + H2SO4 (L) —> H2S2O7 (L)
Oleum obtained from absorption tower is carefully mixed with water to produce sulfuric acid (around 98% pure), H2S2O7 (L) + H20 (L) —> 2 H2SO4 (L)
Uses of sulfuric acid
Main use is the manufacture of fertilisers
Ca3(PO4)2 (s) + 2 H2SO4 (L) + 4 H20 (L) —> Ca(H2PO4)2 (s) + 2 CaSO4.2H20 (s)
Used in lead accumulator batteries, Lab reagent
Fossil fuels
Fossil fuels are removed from the carbon cycle, Burning of fossil fuels releases carbon dioxide into the atmosphere adding extra carbon into the carbon cycle (adding fossil fuels back into the carbon cycle), Approximately 300 G tonnes since the intention of the steam engine has been added into the carbon cycle
Renewable energy
Using something already in the carbon cycle
Effects of increased carbon
Global warming (melting of ice-caps, greenhouse effect), Ocean acidification (decreasing PH, increasing H+ ions)
Coral bleaching
Warm currents kill the algae inside coral, Symbiotic relationship between coral and algae, Coral bleaching is happening more frequently and is killing the great barrier reef
Ocean acidification
Increases its hydrogen ion concentration (Decrease in pH), Decrease its carbonate ion (which animals pull from to make shells meaning many have thinner shells) concentration- issue as crabs etc are bottom of the food chain, Agitation and colder temperatures (colder climates suffer more) assist with CO2 solubility, Decrease of 0.4 pH units means around a 50% loss of carbonates
Equilibria in the ocean reactions
CO2 (g) <—> CO2 (aq)
CO2 (g) + H20 (L) <—> H2CO3 (aq)
H2CO3 (aq) <—> H+ (aq) + HCO3- (aq) High Kc value means it is favoured
HCO3- (aq) <—> H+ (aq) + CO3 2- (aq) Low Kc value means it is less favoured
Equilibria in the ocean
Increasing the concentration of carbon dioxide favours the forward reaction for the first two reactions, Carbonic acid (H2CO3) almost immediately breaks apart meaning there is little to no % in the ocean, Excess H+ ions produced combine with the carbonate ions needed for shells making HCO3 which can’t be used to make shells, There is an accumulation of HCO3 (around 89%) and a decrease in CO3 2-
Calcification
Calcium carbonate is the building block of skeletons and shells of marine organisms, Involves the precipitation of dissolved ions into solid CaCO3 structures
Ca 2+ (aq) + 2HCO3- (aq) <—> CaCO3 + H20 (L) + CO2 (aq)
CO2 (aq) + CO3 21 (aq) + H2O (L) <—> 2 HCO3- (aq)
CaCO3 actually comes from HCO3- ions that become CO3- ions
International responses
Kyoto protocol- 1997, Paris agreement- 2015, Glasgow climate change conference- 2021
