SC19-21 Flashcards
exothermic + endothermic
exothermic releases energy into surrounding + makes bonds
endothermic takes in energy from the surroundings + breaks bonds
what is combustion and what three things does it require
combustion is the burning of a fuel requires: heat fuel oxygen
difference between incomplete and complete combustion
complete combustion - burns a fuel in excess oxygen
incomplete combustion - burns a fuel in restricted oxygen
complete and incomplete combustion equation
complete
fuel + oxygen –> carbon dioxide + water
incomplete
fuel + oxygen –>
1) carbon + water
2) carbon dioxide + water
3) carbon monoxide + water
combustion pollutants
carbon, carbon dioxide, carbon monoxide, sulfur dioxide, nitrogen oxide
acid rain’s pH and how it affects plants and lakes
pH below 5.2
plants - kills ones that can’t grow in acidic soil
lakes - acidifies them and kills small organisms
define cracking + how it works
fractional distillation of crude oil
heats alkane + catalyst (chemical reaction occurs) and small gas molecules collect underwater and are collected in a tube
why is water used in cracking
so the majority of gas doesn’t escape to the rest of the room (if there was no water, the gas would just pass through the air faster and majority would be lost to the surroundings)
what is the atmosphere’s air made of
78% nitrogen
21% oxygen
1% argon
0.03% carbon dioxide + other gases
what the early atmosphere was made of and why
carbon dioxide + water vapour
due to volcanoes
steps of evolution from the early atmosphere
volcanoes emitted co2 and water vapour –> the water vapour cooled
oceans formed –> co2 dissolved in the oceans
single cells organisms photosynthesised with the co2 –> released o2 into the atmosphere which made ozone (o3)
more plants –> more photosynthesis –> more oxygen
