Let's analyze the provided chemical reaction to understand the impact of a change in concentration of one of the reactants. The reaction is:
[tex]\[ 2 \text{NO} (g) + \text{H}_2 (g) \rightarrow \text{N}_2\text{O} (g) + \text{H}_2\text{O} (g) \][/tex]
We need to determine what happens when the concentration of nitrogen monoxide (NO) decreases.
1. Effect on Collision Frequency:
- According to the law of mass action, the rate of a chemical reaction is proportional to the product of the concentrations of the reactants. In this case, the reaction involves nitrogen monoxide (NO) and hydrogen gas (H[tex]$_2$[/tex]).
- If the concentration of NO decreases, there will be fewer NO molecules available in the system.
- Since there are fewer NO molecules, the frequency of collisions between NO molecules and H[tex]$_2$[/tex] molecules will decrease.
2. Effect on Reaction Rate:
- The rate of the forward reaction depends on how frequently the reactant molecules collide with enough energy to react. A decrease in the concentration of NO means that there are fewer successful collisions occurring between NO and H[tex]$_2$[/tex] molecules.
- Therefore, the overall rate of the forward reaction will decrease as well.
Based on this detailed explanation, we can fill in the blanks for the question:
- A decrease in the concentration of nitrogen monoxide decreases collisions between NO and H[tex]$_2$[/tex] molecules.
- The rate of the forward reaction then decreases.
So, the correct answer will be:
```
A decrease in the concentration of nitrogen monoxide decreases collisions between NO and H _2 molecules. The rate of the forward reaction then decreases.
```
