Page 21 - Curriculum Visions Dynamic Book

base: a compound that may be soapy to the touch and that can react with an acid in water to form a salt and water.
decompose: to break down a substance (for example, by heat or with the aid of a catalyst) into simpler components. In such a chemical reaction only one substance
is involved.
kiln: a structure designed for baking minerals. Lime, brick and pottery kilns are all common.
Rotary kiln (red tube)
 In a cement plant one of the larger pieces of equipment is an iron tube, slightly tilted down at one end and slowly rotating. Inside, limestone is roasted using a gas flame. This equipment, known as a rotating kiln, is the industrial equivalent of the process shown opposite.
EQUATION: Calcium carbonate decomposes
Calcium carbonate ➪ calcium oxide + carbon dioxide CaCO3(s) ➪ CaO(s) + CO2(g)
 This picture shows what calcium oxide looks like after it has been cooled and then removed from the kiln.
Also...
Calcium oxide is a strong base and can be used to neutralize acids. Its violent reaction with water makes it unsuitable to be used directly as a soil conditioner (see calcium hydroxide, page 24). However, in dry form it can be used in the manufacture of cement, mortar and concrete.
Calcium carbonate breaks down when heated to form calcium oxide and releases carbon dioxide gas. The technical word for this kind of breakdown is
“thermal decomposition.” However, this reaction is reversible. If carbon dioxide gas flows over calcium oxide, it will re-form calcium carbonate (although it will never again look like the original rock).
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