Page 30 - Curriculum Visions Dynamic Book
P. 30
Nitrogen dioxide
The three most important gases of nitrogen are nitrogen dioxide
(a brown gas that is the cause of the brown part of modern smog), and nitrous and nitric oxides (both colourless gases). All three gases are present in the emissions from vehicles and contribute in various ways to acid rain.
The properties of nitrogen dioxide can be investigated by preparing it in a gas jar in the laboratory or as shown on page 32. Its effects on the environment are discussed on page 34.
A representation of a molecule of nitrogen dioxide gas.
Nitrogen
Nitrogen dioxide is prepared by pouring concentrated nitric acid on to copper turnings.
strong brown colour. When it Oxygen has filled the gas jar it spills
over the sides and sinks down the outside of the jar, creating a sinister brown layer on the bench top.
EQUATION: Copper and nitric acid
Copper + nitric acid ➪ copper nitrate + water + nitrogen dioxide Cu(s) + 4HNO3(conc) ➪ Cu(NO3)2(aq) + 2H2O(l) + 2NO2(g)
Also...
Copper is not very reactive, but it will react with concentrated nitric acid, which acts as an oxidising agent rather than an acid.
As the gas forms, it is a
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