Which equation is a decomposition reaction?

A. [tex] Li_2CO_3 \rightarrow Li_2O + CO_2 [/tex]
B. [tex] Zn + HCl \rightarrow ZnCl_2 + H_2 [/tex]
C. [tex] Na_2O + CO_2 \rightarrow Na_2CO_3 [/tex]
D. [tex] C_6H_{12}O_6 + O_2 \rightarrow CO_2 + H_2O [/tex]



Answer :

Let's start by understanding what a decomposition reaction is.

A decomposition reaction is a type of chemical reaction where one compound breaks down into two or more simpler substances. The general form of a decomposition reaction is:
[tex]\[ AB \rightarrow A + B \][/tex]

Now, let's examine each of the given equations to determine which one fits this description:

1. [tex]\( Li_2CO_3 \rightarrow Li_2O + CO_2 \)[/tex]

Here, one compound (lithium carbonate, [tex]\( Li_2CO_3 \)[/tex]) is breaking down into two simpler substances (lithium oxide, [tex]\( Li_2O \)[/tex], and carbon dioxide, [tex]\( CO_2 \)[/tex]). This fits the form of a decomposition reaction.

2. [tex]\( Zn + HCl \rightarrow ZnCl_2 + H_2 \)[/tex]

This equation shows a single replacement reaction, where zinc ([tex]\( Zn \)[/tex]) replaces hydrogen in hydrochloric acid ([tex]\( HCl \)[/tex]) to form zinc chloride ([tex]\( ZnCl_2 \)[/tex]) and hydrogen gas ([tex]\( H_2 \)[/tex]).

3. [tex]\( Na_2O + CO_2 \rightarrow Na_2CO_3 \)[/tex]

This equation represents a combination reaction, where sodium oxide ([tex]\( Na_2O \)[/tex]) and carbon dioxide ([tex]\( CO_2 \)[/tex]) combine to form sodium carbonate ([tex]\( Na_2CO_3 \)[/tex]).

4. [tex]\( C_6H_{12}O_6 + O_2 \rightarrow CO_2 + H_2O \)[/tex]

This equation is a combustion reaction, where glucose ([tex]\( C_6H_{12}O_6 \)[/tex]) reacts with oxygen ([tex]\( O_2 \)[/tex]) to produce carbon dioxide ([tex]\( CO_2 \)[/tex]) and water ([tex]\( H_2O \)[/tex]).

Therefore, the equation that represents a decomposition reaction is:

[tex]\[ Li_2CO_3 \rightarrow Li_2O + CO_2 \][/tex]