USING RESOURCES #2 Flashcards
what is potable water
potable water is water that’s been treated or is naturally safe for humans to drink
is potable water pure
no as it can contain lots of other dissolved substances
how is water treated from a ground water source
filtration- a wire mesh screens out large twigs for example and then gravel and sand filter out any other bits
sterilisation- the water is sterilised to kill any harmful bacteria or microbes. this can be done by bubbling chlorine gas through it or by using ozone or ultraviolet light
treating sewage
before being treated the sewage is screened
then its allowed to stand in a settlement tank and undergoes sedimentation- the heavier suspended solids sink to the bottom to produce sludge while the lighter effluent floats on the top
the effluent in the settlement tank is removed and treated by biological aerobic digestion, this is when air is pumped through the water to encourage aerobic bacteria to break down organic matter
the sludge from the bottom of the settlement tank is also removed and transferred into large tanks here it gets broken down by bacteria in a process called anaerobic digestion
anaerobic digestion breaks down the organic matter in the sludge releasing methane gas in the process
what is needed to make ammonia
nitrogen and hydrogen
how do you make ammonia
the haber process
equation for the haber process
nitrogen + hydrogen ——- ammonia
the haber process
nitrogen is obtained from the air
the hydrogen comes from reacting methane with steam to form hydrogen and carbon dioxide
the reactant gases are passed over an iron catalyst. A high temperature (450 degrees) and a high pressure (200 atmospheres) are used
because the reaction is reversible some of the ammonia produced converts back into hydrogen and nitrogen again, it eventually reaches a dynamic equilibrium
the ammonia is formed as a gas but as it cools ina condenser it liqefis and is removed, the unused hydrogen and nitrogen are recycled so nothing is wasted
the ammonia can then be used to make ammonium nitrate
what are the industrial conditions used in the haber process and why
a temperature of 450 degrees is used because this is high enough to ensure a fast rate of reaction without decreasing the yield of ammonia by too much. A pressure of 200 atm is used in order to maximise the rate and the yield of the reaction. Higher pressure would be too expensive, an iron catalyst is used in order to speed up the rate of reaction
what are the three main essential elements in fertilisers
nitrogen
phosphorous
potassium
what happens if plants don’t get enough n p pin fertilisers
it affects their growth and their life processes are affected
why might these elements be missing from the soil
if they’ve been used up by a previous crop
what do ferilisers do
fertilisers replace these missing elements or provide more of them, this helps to increase the crop yield as the crops can grow faster and bigger, eg fertilisers add more nitrogen to plant proteins which makes the plants grow faster
what are npk fertilisers
are formulations containing salts of nitrogen , phosphorus and potassium in the right percentages of these elements
why is ammonium nitrate a good fertiliser
because it has nitrogen from two sources
