Video Transcript
A teacher demonstrates the
reduction of copper(II) oxide to students in a class using 2.0 grams of copper
oxide. After the experiment is finished,
the teacher reweighs the chemicals in the reduction tube. What is the mass of the solid
chemicals? (A) The same, 2.0 grams. (B) Less than 2.0 grams. (C) More than 2.0 grams.
Copper(II) oxide is a fascinating
compound that has the chemical formula CuO. It reacts with hydrogen at high
temperatures and makes copper and water products. The equation describes the reaction
between hydrogen gas and solid copper(II) oxide. Reduction describes a chemical
compound losing its oxygen. The copper oxide reduces to copper
as it reacts with hydrogen because it loses oxygen. The lost oxygen combines with
hydrogen and makes water. The copper(II) oxide turns into
copper metal during the chemical reaction process.
The experiment has black copper(II)
oxide in a reduction tube. Hydrogen gas continuously enters
the reduction tube and passes over the copper(II) oxide compound. The temperature is high in the
reduction tube because of the heat source. The copper(II) oxide gets hot and
reacts with available hydrogen molecules. It loses oxygen and makes solid
copper metal and water vapor.
The starting solid CuO material is
a combination of both copper and oxygen. The product, solid copper, has the
same number of copper atoms but does not have any oxygen. The solid mass decreases during the
chemical reaction process as the oxygen is lost. It is initially two grams and gets
lower than this as copper(II) oxide reduces to copper. Option (B) is the correct answer to
this question. The correct answer is less than 2.0
grams.
