Consider the chemical equations shown here.
[tex]
\begin{array}{l}
2 Na(s)+Cl_2(g) \rightarrow 2 NaCl(s) \
4 Na(s)+O_2(g) \rightarrow 2 Na_2 O(s)
\end{array}
[/tex]
What is the overall equation for the reaction that produces NaCl and [tex]O _2[/tex] from [tex]Na _2 O[/tex] and [tex]Cl _2[/tex]?
A. [tex]Na _2 O ( s )+ Cl _2(g) \rightarrow NaCl ( s )+ O _2(g)[/tex]
B. [tex]2 Na _2 O ( s )+ Cl _2(g) \rightarrow 2 NaCl ( s )+ O _2(g)[/tex]
C. [tex]2 Na _2 O ( s )+2 Cl _2(g) \rightarrow 4 NaCl ( s )+ O _2(g)[/tex]
Answer (2)
Reverse the second given equation.
Multiply the first given equation by 2.
Add the modified equations to eliminate N a ( s ) .
Simplify the equation to obtain the balanced equation: 2 N a 2 O ( s ) + 2 C l 2 ( g ) → 4 N a Cl ( s ) + O 2 ( g ) .
The overall equation is 2 N a 2 O ( s ) + 2 C l 2 ( g ) → 4 N a Cl ( s ) + O 2 ( g )
Explanation
Understanding the Problem We are given two chemical equations:
2 N a ( s ) + C l 2 ( g ) → 2 N a Cl ( s )
4 N a ( s ) + O 2 ( g ) → 2 N a 2 O ( s )
We want to find the overall equation for the reaction that produces N a Cl and O 2 from N a 2 O and C l 2 . This means we want to find the balanced equation for the reaction:
N a 2 O ( s ) + C l 2 ( g ) → N a Cl ( s ) + O 2 ( g )
Manipulating the Equations To find the overall equation, we need to manipulate the given equations to obtain the desired reaction. First, let's reverse the second equation:
2 N a 2 O ( s ) → 4 N a ( s ) + O 2 ( g )
Next, multiply the first equation by 2:
4 N a ( s ) + 2 C l 2 ( g ) → 4 N a Cl ( s )
Now, add the modified equations:
2 N a 2 O ( s ) + 4 N a ( s ) + 2 C l 2 ( g ) → 4 N a ( s ) + O 2 ( g ) + 4 N a Cl ( s )
Finding the Balanced Equation We can simplify the equation by removing 4 N a ( s ) from both sides:
2 N a 2 O ( s ) + 2 C l 2 ( g ) → 4 N a Cl ( s ) + O 2 ( g )
This is the balanced equation for the reaction that produces N a Cl and O 2 from N a 2 O and C l 2 .
Final Answer The overall balanced equation is:
2 N a 2 O ( s ) + 2 C l 2 ( g ) → 4 N a Cl ( s ) + O 2 ( g )
Therefore, the correct answer is:
2 N a 2 O ( s ) + 2 C l 2 ( g ) → 4 N a Cl ( s ) + O 2 ( g )
Examples
In industrial chemistry, understanding how to balance chemical equations is crucial for optimizing the production of desired compounds while minimizing waste. For example, in the chlor-alkali process, sodium chloride (NaCl) is electrolyzed to produce chlorine gas, hydrogen gas, and sodium hydroxide (NaOH). Balancing the chemical equation ensures that the correct stoichiometric ratios of reactants are used, leading to efficient and cost-effective production. Similarly, in the production of fertilizers, balancing equations helps determine the precise amounts of nitrogen, phosphorus, and potassium needed to create a fertilizer blend that maximizes crop yield.
The overall balanced equation for the production of NaCl and O_2 from Na_2O and Cl_2 is 2 N a 2 O ( s ) + 2 C l 2 ( g ) → 4 N a Cl ( s ) + O 2 ( g ) . Therefore, the correct answer is option C.
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