Video Transcript
Metal catalysts are commonly used
to help increase the rate of a chemical reaction. A student weighs out a block of a
metal catalyst before and after being used in a chemical reaction. This is shown in the image
below. What should the mass of the
catalyst be after the reaction?
Catalysts are valuable additions to
many chemical reactions, especially important reactions that happen on an industrial
scale. We are told in the question that
the metal catalyst used can help increase the rate of a chemical reaction. The rate of a chemical reaction is
a measure of the speed at which the concentrations of the reactants decrease and the
products increase. The rate of reaction can commonly
be affected by the temperature of the reaction, the concentration of the reactants
or products, the surface area, pressure, or the presence of a catalyst.
Metal catalysts provide a special
surface where the reactant molecules are concentrated together so that they can
react more easily. The catalyst is chemically involved
in the reaction at this point. After the products have been
produced and released from the surface of the catalyst, the catalyst will have the
same structure and properties as it did before the reaction took place. As the catalyst is not chemically
changed or used up during the chemical reaction, it can be used again and again.
Not all catalysts provide a surface
on which the reaction can occur, and some catalysts are used to decrease the rate of
a chemical reaction instead of increase it. But all catalysts can be defined as
a substance that changes the rate of reaction without undergoing a permanent
chemical change.
In our example, the block of metal
is acting as a catalyst, so it should be the same before and after the chemical
reaction takes place. This means that we should expect
the mass of the block of metal to be the same before and after the reaction. If the mass of the catalyst before
the reaction is 1.5 grams, then the mass of the catalyst after the reaction should
also be 1.5 grams.
