Page 14 - Curriculum Visions Dynamic Book

Copper as a metal
About nine million tonnes of copper are used every year in a wide variety of ways. About half of all copper is used in the electrical industry (see next page). Copper is also used for
water pipes, roofing, locks and hinges, coins, and vehicle radiators.
Many of these uses have come about because, of all the common metals, copper
is outstanding in its resistance to attack
by oxygen and water. Copper only changes
to copper oxide when the temperature reaches 300°C. It is not corroded by water
or steam, which is why it can be used for
hot and cold water systems and central heating and air conditioning systems. It is not even affected by most dilute acids, although concentrated nitric acid reacts violently with copper, as shown below.
EQUATION: Copper and fuming nitric acid
Copper turnings + fuming nitric acid ➪ copper nitrate + water + nitrogen dioxide Cu(s) + 4HNO3(l) ➪ Cu(NO3)2(s) + 2H2O(l) + 2NO2(g)
blue
 Heated copper compounds produce a characteristic green–blue flame.
 The picture on the far left shows fuming concentrated nitric acid being poured on to copper turnings (finely divided copper that provides a large surface area for fast reaction). The picture on the near left shows the resulting reaction. The copper is transformed into blue copper nitrate and large amounts of nitrogen dioxide are given off.
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