Consider the following intermediate chemical equations:
[tex]
\begin{array}{l}
C(s)+\frac{1}{2} O_2(g) \rightarrow CO(g) \\
CO(g)+\frac{1}{2} O_2(g) \rightarrow CO_2(g)
\end{array}
[/tex]
When you form the final chemical equation, what should you do with CO?
A. Cancel out CO because it appears as a reactant in one intermediate reaction and a product in the other intermediate reaction.
B. Add the two CO molecules together and write them as reactants in the final chemical reaction.
C. Write CO only once as a reactant in the final chemical reaction.
D. Write CO as a reactant and a product in the final chemical reaction.
Answer (1)
To form the final chemical equation:
Add the two intermediate equations.
Identify CO as a product in the first equation and a reactant in the second equation.
Cancel out CO because it appears on both sides of the combined equation.
The final equation is: C ( s ) + O 2 ( g ) → C O 2 ( g ) .
Explanation
Understanding the Problem We are given two chemical equations and asked what to do with CO when forming the final chemical equation. The key is to understand how to combine chemical equations and how to treat intermediate species.
Adding the Equations To form the final chemical equation, we add the two intermediate equations together:
C ( s ) + 2 1 O 2 ( g ) → CO ( g ) CO ( g ) + 2 1 O 2 ( g ) → C O 2 ( g )
Adding these two equations gives:
C ( s ) + 2 1 O 2 ( g ) + CO ( g ) + 2 1 O 2 ( g ) → CO ( g ) + C O 2 ( g )
Canceling Common Species Now, we simplify the equation by canceling out any species that appear on both sides of the equation. In this case, CO ( g ) appears on both the reactant and product sides. Therefore, we cancel it out:
C ( s ) + 2 1 O 2 ( g ) + CO ( g ) + 2 1 O 2 ( g ) → CO ( g ) + C O 2 ( g )
Final Equation Combining the oxygen terms, we get the final balanced equation:
C ( s ) + O 2 ( g ) → C O 2 ( g )
Conclusion Therefore, CO should be canceled out because it appears as a reactant in one intermediate reaction and a product in the other intermediate reaction.
Examples
In environmental science, understanding how to combine chemical equations is crucial for modeling complex processes like combustion or atmospheric reactions. For example, when assessing the impact of burning fossil fuels, we combine intermediate reactions to determine the overall products released into the atmosphere, such as carbon dioxide and water vapor. This helps in evaluating the environmental consequences and developing strategies for pollution control.
