Page 42 - Curriculum Visions Dynamic Book

Phosphoric acid and phosphates
Phosphorus, in the form of compounds called Using phosphoric acids
phosphates, occur in all living things. They play a vital role in allowing both plants and animals to transfer energy.
Calcium phosphate is also important to bone- making, comprising about 1.5 kilograms of every adult human skeleton. Phosphates are also found
When phosphoric acid is reacted with bases a range of useful products results.
When the base contains sodium (as in sodium hydroxide) the resulting salt is trisodium phosphate, used in washing powders for many
in the chromosomes involved in reproduction. years. When reacted with
phosphoric acid is also used to produce the tart taste in some soft drinks.
Because of its crucial role to life, phosphorus
is a key element in fertilisers. Bone meal, crushed
animal bones, is a traditional way of returning Phosphoric acid is a hard,
phosphorus to the soil. The alternative supply is
from phosphate rock (apatite), which is mined in
Florida and Morocco. This is crushed and treated In very low concentrations,
to produce the fertiliser called superphosphate.
EQUATION: Phosphoric acid rust-inhibitor
an organic compound the phosphate is useful as a filler for small cracks.
glassy solid, the basis of the hard surface for some kinds of enamel.
Phosphoric acid + iron oxide ➪ iron phosphate + water 2H3PO4(aq) + Fe2O3(s) ➪ 2FePO4(s) + 3H2O(aq)
Preparing phosphoric acid
Crushed phosphate rock (calcium phosphate)
is reacted with sulphuric acid (as in making superphosphate). Further treatment with sulphuric acid, and removal of the gypsum precipitate by filtering, leaves a 60–70% solution of phosphoric acid.
 A representation of a phosphoric acid molecule.
Rust inhibitors are compounds such as phosphoric acid.
The reaction between the acid and iron oxide converts the iron oxide layer to iron phosphate, a glassy, insoluble material that is gastight when it dries.
Hydrogen
Phosphorus
Oxygen
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