Answer
The compound in the blank is $H_2$.
This reaction is products-favored, because this side has the weaker acid and base.
Work Step by Step
1. Identify the other compound that is next to the blank, on the same side:
- It is $OH^-$;
2. Is it acting as an acid or as a base?
- As a base, because it is receiving one proton.
3. If the other compound is a base, the blank should be an acid.
4. The conjugate pair of $OH^-$ is $H_2O$, therefore, the conjugate pair of the blank compound should be $H^-$.
5. Since the compound that is missing is an acid, $H^-$ should be its conjugate base.
6. Determine the conjugate acid of $H^-$.
- If we add a proton to $H^-$, it turns to $H_2$, therefore, this is the compound in the blank.
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1. To determine which side the reaction favors, identify the side with the weaker compounds.
Acids: $H_2$ and $H_2O$
** You can find the constants values on table 14.2, on page 624.
- $H_2$ is weaker;
Bases: $H^-$ and $OH^-$
- $OH^-$ is weaker.
Therefore, the products side is favored.
