In balancing the reaction involving BCl3 and H2, what is the coefficient for HCl in lowest terms?

• A. 1
• B. 2
• C. 3
• D. 6

Answer: (D)

To determine the correct coefficient for HCl in the balanced chemical reaction involving BCl3 and H2, we first need to write out the balanced equation. The reaction can be represented as follows:

[ \text{BCl}_3 + \text{H}_2 \rightarrow \text{B} + \text{HCl} ]

In this reaction, boron trichloride (BCl3) reacts with hydrogen gas (H2) to produce boron (B) and hydrochloric acid (HCl).

For balancing the reaction, we note that BCl3 has three chlorine atoms. Each HCl molecule contains one chlorine atom, so to balance the chlorines from BCl3, we will need three HCl molecules.

The hydrogen in HCl must also be balanced. Since we have two hydrogen atoms in H2 and we need to produce three hydrogen atoms (one for each molecule of HCl), we need a total of three H2 molecules for the stoichiometry to match.

Thus, the balanced equation becomes:

[ \text{BCl}_3 + 3\text{H}_2 \rightarrow \text{B} + 3\text{HCl} ]

In terms