Video Transcript
Why are catalysts used in chemical
reactions? (A) To reduce the amount of waste
produced. (B) To ensure the reaction is
safe. (C) To increase the rate of
reaction. (D) To produce more product
overall. (E) To improve the purity of the
products.
A catalyst is a substance that
speeds up a chemical reaction without being used up. They have essentially the same
chemical and physical properties before and after they make reactants turn into
products. Lots of manufacturers use catalysts
to speed up an otherwise slow chemical reaction to increase productivity.
In industry an iron metal catalyst
is used to make ammonia very rapidly from nitrogen and hydrogen gas. Another example is using a
nickel-based catalyst to speed up hydrogenation reactions.
Catalysts speed up chemical
reactions because they lower energy barriers for the production of product
molecules. Let us consider how a catalyst
changes the energy barrier for a chemical reaction. We will draw an energy level
diagram. We will draw one line for the
reactants and another one for the products. The product line has a lower
position relative to the reactant line because it has a lower overall energy.
We will now draw a line that shows
products made without a catalyst. The peak represents the maximum
amount of energy the reactants must gain to turn into products. Let us now draw another line that
shows products made with a catalyst. The reactants need less energy to
turn into products in the presence of a catalyst. Catalysts make reactants turn into
products at a fast rate because they lower energy barriers for chemical
reactions.
Option (C) must be the correct
answer to this question. It correctly states that people use
a catalyst to speed up a chemical reaction. “To increase the rate of reaction”
is the correct answer.
