Which of the following is an example of a synthesis reaction?

A. [tex]H_2 + Br_2 \rightarrow 2 HBr[/tex]
B. [tex]NaCl \rightarrow Na^+ + Cl^-[/tex]
C. [tex]2 H_2O + 2 Na \rightarrow 2 NaOH + H_2[/tex]
D. [tex]Mg + H_2SO_4 \rightarrow MgSO_4 + H_2[/tex]



Answer :

To determine which of the given reactions is an example of a synthesis reaction, let's first understand what a synthesis reaction is.

A synthesis reaction, also known as a combination reaction, occurs when two or more reactants combine to form a single product.

Let's analyze each option to see if it fits this definition:

A. [tex]\( H_2 + Br_2 \rightarrow 2 HBr \)[/tex]
- Here, hydrogen gas ([tex]\(H_2\)[/tex]) and bromine gas ([tex]\(Br_2\)[/tex]) are combining to form hydrogen bromide ([tex]\(HBr\)[/tex]).
- We see that two reactants are forming a single product.
- This is a synthesis reaction.

B. [tex]\( NaCl \rightarrow Na^+ + Cl^- \)[/tex]
- This reaction involves the dissociation of sodium chloride ([tex]\(NaCl\)[/tex]) into its ions.
- It's not forming a new single product but breaking down into two different ions.
- This is not a synthesis reaction.

C. [tex]\( 2 H_2O + 2 Na \rightarrow 2 NaOH + H_2 \)[/tex]
- In this reaction, water ([tex]\(H_2O\)[/tex]) and sodium ([tex]\(Na\)[/tex]) react to form sodium hydroxide ([tex]\(NaOH\)[/tex]) and hydrogen gas ([tex]\(H_2\)[/tex]).
- This results in two products rather than a single product.
- This is not a synthesis reaction.

D. [tex]\( Mg + H_2SO_4 \rightarrow MgSO_4 + H_2 \)[/tex]
- Magnesium ([tex]\(Mg\)[/tex]) and sulfuric acid ([tex]\(H_2SO_4\)[/tex]) react to form magnesium sulfate ([tex]\(MgSO_4\)[/tex]) and hydrogen gas ([tex]\(H_2\)[/tex]).
- This also results in two products.
- This is not a synthesis reaction.

From this analysis, the appropriate example of a synthesis reaction is:

A. [tex]\(H_2 + Br_2 \rightarrow 2 HBr\)[/tex]

This reaction clearly fits the definition of a synthesis reaction where two reactants combine to form a single product.