Which equation is an example of a synthesis reaction?

A. [tex]CH _4+2 O _2 \rightarrow 2 H _2 O + CO _2[/tex]

B. [tex]HNO _3+ KOH \rightarrow KCl + H _2 O[/tex]

C. [tex]2 Li + CaCl _2 \rightarrow 2 LiCl + Ca[/tex]

D. [tex]S + O _2 \rightarrow SO _2[/tex]



Answer :

To identify which equation is an example of a synthesis reaction, let's first define what a synthesis reaction is. In a synthesis reaction, two or more simple substances combine to form a more complex product. The general form is A + B → AB.

Now, let's analyze each of the given options:

A. [tex]\(CH_4 + 2 O_2 \rightarrow 2 H_2O + CO_2\)[/tex]

This equation represents the combustion of methane where methane and oxygen react to produce water and carbon dioxide. This is a combustion reaction, not a synthesis reaction.

B. [tex]\(HNO_3 + KOH \rightarrow KCl + H_2O\)[/tex]

This equation is a neutralization reaction where an acid (HNO_3) reacts with a base (KOH) to produce a salt (KCl) and water (H_2O). This is not a synthesis reaction.

C. [tex]\(2 Li + CaCl_2 \rightarrow 2 LiCl + Ca\)[/tex]

Here, lithium reacts with calcium chloride to produce lithium chloride and calcium. This is a single replacement (or displacement) reaction, not a synthesis reaction.

D. [tex]\(S + O_2 \rightarrow SO_2\)[/tex]

In this equation, sulfur (S) combines with oxygen (O_2) to form sulfur dioxide (SO_2), which is a single compound. This fits the criteria for a synthesis reaction, as two simple substances are combining to form a more complex product.

Therefore, the correct answer is:

D. [tex]\(S + O_2 \rightarrow SO_2\)[/tex]