In the given chemical equation, What is the missing coefficient to balance the equation?__ H2 +    1 Cl2 →   2 HCl

1. Break Down the Problem

To balance the chemical equation, we need to ensure that the number of each type of atom on the reactant side (left) is equal to the number on the product side (right).

2. Relevant Concepts

The equation given is: $\_\_ H_2 + 1 Cl_2 \rightarrow 2 HCl$

In this reaction:

• Reactants: $H_2$ and $Cl_2$
• Product: $HCl$

We will analyze and balance each element involved.

3. Analysis and Detail

• Count the Atoms in the Products:

  • $HCl$: There are 2 hydrogen atoms and 2 chlorine atoms from the 2 $HCl$ produced.

• Count the Atoms in the Reactants:

  • We have 2 hydrogen atoms from $H_2$ and 2 chlorine atoms from $Cl_2$ (1 molecule of $Cl_2$ provides 2 chlorine atoms).

To balance the equation, we examine what coefficient we can place in front of $H_2$:

1. Currently, we have:
   • $H$: 2 (from H2) vs 2 (in 2 HCl) --> balanced
   • $Cl$: 2 (from Cl2) vs 2 (in 2 HCl) --> balanced

4. Verify and Summarize

Since both hydrogen and chlorine are balanced with their respective molecules and coefficients, the missing coefficient for $H_2$ is 1.

Final Answer

The missing coefficient to balance the equation is 1. Thus, the balanced equation is: $1 H_2 + 1 Cl_2 \rightarrow 2 HCl$