An experimenter attempts to carry out a single replacement reaction between solid iron and a solution of magnesium bromide.
Which is more reactive, iron or magnesium?
Which of the following equations correctly predicts the products of the reaction?
i. [tex]Fe _{( s )}+ MgBr _{2( aq )} \rightarrow Br _{2( l )}+2 MgFe _{( aq )}[/tex]
ii. [tex]Fe _{( s )}+ MgBr _{2( aq )} \rightarrow FeMgBr _{2(s)}[/tex]
iii. [tex]Fe _{( s )}+ MgBr _{2( aq )} \rightarrow Mg _{( s )}+ FeBr _2( aq )[/tex]
iv. [tex]Fe _{( s )}+ MgBr _{2( aq )} \rightarrow[/tex] no reaction
Answer (2)
Magnesium is more reactive than iron.
Iron cannot displace magnesium from magnesium bromide.
Therefore, no reaction occurs.
The correct equation is: F e ( s ) + M g B r 2 ( a q ) → no reaction
Explanation
Understanding Reactivity In a single replacement reaction, a more reactive metal can displace a less reactive metal from its compound. To determine whether iron or magnesium is more reactive, we need to refer to the activity series of metals.
Determining Relative Reactivity Magnesium is higher in the activity series than iron. This means magnesium is more reactive than iron. Therefore, iron cannot displace magnesium from magnesium bromide ( M g B r 2 ).
Predicting the Reaction Outcome Since iron is less reactive than magnesium, no reaction will occur when solid iron is added to a solution of magnesium bromide.
Final Answer Therefore, the correct answer is:
Magnesium is more reactive.
The correct equation is:
iv. F e ( s ) + M g B r 2 ( a q ) → no reaction
Examples
Single replacement reactions are commonly used in industrial processes, such as extracting metals from their ores. For example, copper can be extracted from copper sulfate solution by adding iron. The more reactive iron displaces copper from the solution, resulting in the formation of iron sulfate and solid copper. This principle is also applied in corrosion prevention, where a more reactive metal is used to protect a less reactive metal from corrosion.
Magnesium is more reactive than iron, which means iron cannot displace magnesium from magnesium bromide. The correct reaction equation is: F e ( s ) + M g B r 2 ( a q ) → no reaction . Thus, the chosen multiple-choice option is iv.
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