Video Transcript
Some of the following copper
compounds can be thermally decomposed; others are thermally stable: Cu(OH)2, CuBr2,
CuCO3, CuSO4, CuCl2, CuO, and CuS. Of those that decompose, which
product is common in all cases? (A) Cu, (B) Cu2O, (C) O2, (D) CuO,
or (E) CO2.
If a compound has thermally
decomposed, it is said to have undergone thermal decomposition, where thermal
decomposition is the breaking down of a substance when heated to form two or more
other substances. There are different copper
compounds that are able to undergo thermal decomposition reactions. In the list of substances given to
us, copper hydroxide, copper carbonate, and copper sulfate are all capable of
undergoing decomposition when heated.
For each of these substances, the
decomposition produces a different gas. In the case of the hydroxide, water
in the form of steam is released. With the carbonate, carbon dioxide
is released. And finally, with the sulfate,
acidic sulfur trioxide gas is released. But despite these different gases
being produced, all three thermal decompositions produce the black solid copper(II)
oxide. So the answer to the question “Of
those that decompose, which product is common in all cases?” is (D) CuO, or
copper(II) oxide.
