So far in this lesson, you have learned the characteristics of five types of chemical reactions. Being able to identify the basic characteristics of the five types of reactions allows you to classify chemical reactions.
How well do you know the characteristics of the five types of reactions? Find out by completing this activity. Match the reaction type on the left with the correct description on the right.
Let's Practice
Now it's time to practice classifying chemical reactions. Answer the question on each tab, then check your answer.
If you need a periodic table, click below to open an interactive periodic table or to download a PDF.
Hydrogen peroxide \((\text{H}_{2}\text{O}_{2})\) is a widely used disinfecting solution for minor cuts and scrapes. It is always kept in a dark brown bottle because hydrogen peroxide needs to be protected from light. If it isn't protected it will gradually break down into water and oxygen.
What type of reaction is being described in this example?
Decomposition
If you need help arriving at this answer, click the Solution button.
There is only one reactant: \(\text{H}_{2}\text{O}_{2}\). It is broken down into simpler compounds: \(\text{H}_{2}\text{O}\) and \(\text{O}_{2}\).
Metals made of iron will have rust (iron oxide) form on the surface when exposed to air as represented by the following chemical equation:
\(2 \text{Fe}_{(\text{s})} + \text{O}_{2\text{(g)}} \rightarrow 2 \text{FeO}_{(\text{s})}\)
What type of reaction is being described in this example?
Synthesis
If you need help arriving at this answer, click the Solution button.
Iron and oxygen form one product: rust \((\text{FeO})\).
Sodium chloride \(\text{(NaCl)}\) reacts with silver sulfate \((\text{Ag}_{2}\text{SO}_{4})\) as represented by the following chemical equation:
\(2 \text{NaCl} + \text{Ag}_{2}\text{SO}_{4} \rightarrow 2 \text{AgCl} + \text{Na}_{2}\text{SO}_{4}\)
What type of reaction is being described in this example?
Double replacement
If you need help arriving at this answer, click the Solution button.
The cations, \(\text{Na}\) and \(\text{Ag}\), switch places to form two new product compounds.
A major component of smog is nitrogen dioxide, which is a toxic gas with a sharp odor. It forms when nitric oxide—from sources such as car exhaust—reacts with oxygen in the air.
What type of reaction is being described in this example?
Synthesis
If you need help arriving at this answer, click the Solution button.
Two reactants, nitric oxide \((\text{NO}_{(g)})\) and oxygen \((\text{O}_{2\text{(g)}})\), produce one product, nitrogen dioxide \((\text{NO}_{2\text{(g)}})\).
Solid metal sodium and chlorine gas will react to form the common household product table salt (sodium chloride) as represented by the following chemical equation:
\(2 \text{Na}_{(\text{s})} + \text{Cl}_{2(\text{g})} \rightarrow 2 \text{NaCl}_{(\text{s})}\)
What type of reaction is being described in this example?
Synthesis
If you need help arriving at this answer, click the Solution button.
One more complex product, sodium chloride, is produced.
A reaction occurs when potassium \((\text{K})\) reacts with water \((\text{H}_{2}\text{O})\). A colorless solid compound named potassium hydroxide \((\text{KOH})\) forms, and hydrogen gas \((\text{H}_{2})\) is set free. The equation for the reaction is:
\(2 \text{K} + 2 \text{H}_{2}\text{O} \rightarrow 2 \text{KOH} + \text{H}_{2}\)
What type of reaction is being described in this example?
Single replacement
If you need help arriving at this answer, click the Solution button.
One of the reactants, potassium, is a single element and not a compound. It replaces the hydrogen because they are both able to form cations.
