The production of concrete requires cement. Almost all cement is made by heating clay minerals and limestone together in a kiln, a type of oven that can reach high temperatures.

Question

The limestone contains calcium carbonate
(CaCO3)
. When limestone is heated to about 1,500°C, it breaks into carbon dioxide gas
(CO2)
and calcium oxide
(CaO)
, or quicklime. The chemical reaction below shows how quicklime is made.
Ca
C
O
3
C
O
2
+
Ca
O
Select the true statements.

A.making quicklime is a chemical change
B.low temperatures are required to make quicklime
C. carbon dioxide is produced when calcium carbonate breaks down
D,quicklime is used to make limestone

Answer 1

Let's evaluate each statement:

A. Making quicklime is a chemical change.
True. The process of heating calcium carbonate to produce calcium oxide and carbon dioxide is a chemical change because the original substance (calcium carbonate) is transformed into different substances (calcium oxide and carbon dioxide).

B. Low temperatures are required to make quicklime.
False. High temperatures (around 1,500°C) are required to decompose calcium carbonate into quicklime.

C. Carbon dioxide is produced when calcium carbonate breaks down.
True. The reaction shows that carbon dioxide gas (CO2) is a product when calcium carbonate (CaCO3) is heated.

D. Quicklime is used to make limestone.
False. Quicklime (calcium oxide) is not used to make limestone; rather, limestone is a raw material that is heated to produce quicklime.

Summary of True Statements: A and C.