Video Transcript
Malachite is an impure ore used to
form copper(II) oxide. The production of copper(II) oxide
involves roasting the malachite in a large furnace at high temperatures. What chemical must be present in
malachite to form copper(II) oxide during the reactions that take place inside the
furnace? (A) Copper(II) carbonate, (B)
copper chloride, (C) copper(II) oxide, (D) copper metal, or (E) copper sulfide.
The question tells us that
malachite, which is a copper ore with a characteristic green color, is heated to
produce copper(II) oxide. So we need to know what type of
compound produces oxides upon heating. For copper oxide to be present at
the end of the roasting process, a copper compound capable of thermal decomposition
must have been present in the malachite, where thermal decomposition is the breaking
down of a substance when heated to form two or more other substances. A metal carbonate will thermally
decompose to produce a metal oxide and carbon dioxide. As copper is a metal, then a copper
oxide must be a metal oxide.
Since metal carbonates thermally
decompose to produce metal oxides, then the chemical in malachite that forms the
copper(II) oxide must be a metal carbonate. So it’s copper(II) carbonate that
thermally decomposes to produce copper(II) oxide and also carbon dioxide. So the answer to the question “What
chemical must be present in malachite to form copper(II) oxide?” is (A) copper(II)
carbonate, which does actually have a characteristic green color.
