An experimenter attempts to carry out a single replacement reaction between chlorine gas and a solution of sodium bromide.
Which is more reactive - chlorine or bromine?
Which of the following equations correctly predicts the products of the reaction?
i. [tex]Cl _{2(g)}+2 NaBr _{( aq )} \rightarrow Br _{2( l )}+2 NaCl _{( aq )}[/tex]
ii. [tex]Cl _2(g)+ NaBr _{( aq )} \rightarrow NaBrCl _2(s)[/tex]
iii. [tex]Cl _{20}+2 NaBr _{( aq )} \rightarrow 2 Na _{( s )}+2 BrCl _{( aq )}[/tex]
iv. [tex]Cl _{2(g)}+ NaBr _{( aq )} \rightarrow[/tex] no reaction
Answer (2)
Chlorine is more reactive than bromine.
Chlorine will displace bromine from sodium bromide solution.
The balanced chemical equation for the reaction is C l 2 ( g ) + 2 N a B r ( a q ) → B r 2 ( l ) + 2 N a C l ( a q ) .
Therefore, the correct equation is i. C l 2 ( g ) + 2 N a B r ( a q ) → B r 2 ( l ) + 2 N a C l ( a q )
Explanation
Determining Relative Reactivity In a single replacement reaction, a more reactive element replaces a less reactive element in a compound. To determine whether chlorine or bromine is more reactive, we need to consider their positions in the halogen group (Group 17) of the periodic table. Reactivity decreases as you go down the group. Since chlorine (Cl) is above bromine (Br) in the periodic table, chlorine is more reactive than bromine.
Predicting the Products Now, let's predict the products of the reaction between chlorine gas ( C l 2 ) and sodium bromide ( N a B r ) solution. Since chlorine is more reactive than bromine, it will displace bromine from the sodium bromide solution. This means chlorine will take the place of bromine, forming sodium chloride ( N a Cl ) and elemental bromine ( B r 2 ).
Identifying the Correct Equation We need to identify the correct balanced chemical equation for this reaction. The general form of the reaction is: C l 2 + N a B r → N a Cl + B r 2 To balance this equation, we need two molecules of N a B r to react with one molecule of C l 2 to produce two molecules of N a Cl and one molecule of B r 2 . The balanced equation is: C l 2 ( g ) + 2 N a B r ( a q ) → 2 N a C l ( a q ) + B r 2 ( l )
Selecting the Correct Equation Comparing the balanced equation with the given options, we find that option i matches the predicted products and stoichiometry: C l 2 ( g ) + 2 N a B r ( a q ) → B r 2 ( l ) + 2 N a C l ( a q )
Examples
Single replacement reactions are commonly used in industrial processes, such as the extraction of metals from their ores. For example, copper can be extracted from copper sulfate solution by reacting it with iron. The more reactive iron replaces copper in the solution, forming iron sulfate and elemental copper. This principle is also used in water purification, where chlorine is used to disinfect water by reacting with and neutralizing harmful substances.
Chlorine is more reactive than bromine, allowing it to displace bromine from sodium bromide solution. The correct equation for the reaction is: C l 2 ( g ) + 2 N a B r ( a q ) → B r 2 ( l ) + 2 N a C l ( a q ) , making option i the correct choice. Thus, the final answer is: C l 2 ( g ) + 2 N a B r ( a q ) → B r 2 ( l ) + 2 N a C l ( a q ) .
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