Air And Water Flashcards
What was earth’s early atmosphere composed of and why?
CO² and N² produced by volcanoes
Led to a very hot earth
How did the oceans form?
Water vapour from volcanoes rose into clouds, condensed and fell as rain, and icy comets melted after hitting earth
How did photosynthesis change the world?
Algae and plants all photosynthesised, filling atmosphere with O², killing off many O² intolerant species, and giving rise to animals who needed O² to respire
Where did all the CO² go?
C mainly went into plant and animal matter, and O into atmosphere and the ocans
CO² also dissolved into oceans
How does the greenhouse effect work?
Short wave length radiation from sun is mainly deflected from earth as long wave radiation, but excess amounts of greenhouse gases traps more and more of this radiation, heating up earth
What is the composition of the modern atmosphere?
78% N²
21% O²
<1% Ar
0.04% CO²
What is Potable water?
Drinkable water, but not always pure, might contain dissolved minerals
What is sedimentation?
Letting bigger particles sink to bottom before collecting clearer water
What is filtration?
Filtering out smaller particles, often through sand
What is sterilisation?
Using chemicals or light to kill pathogens
What colour does CoCl² (cobalt chloride) paper go in water?
Blue to pink
What may still be present in treated water?
Dead pathogens, leftover chlorine, dissolved salts and minerals
What is chlorine used for in water treatment
Sterilisation
Is safe for human consumption in small amounts
What colour does litmus paper go in presence of chlorine gas?
Red to blue, but is then bleached by HClO, so goes white
Cl² + H²O -> HCl + HClO
Why is distillation costly?
Heating and applying pressure
