When does a single replacement reaction occur?

1 Answer

Answer:

A single replacement reaction occurs when an element reacts with a compound to produce a new element and a new compound.

Explanation:

A single replacement reaction occurs when an element reacts with a compound to produce a new element and a new compound.

There are two types of single replacement reactions:

A metal replaces another metal that is in solution:
#"A" + "BC" → "B" + "AC"#
Example: #"Zn" + "CuCl"_2→ "Cu" + "ZnCl"_2#

A halogen replaces another halogen that is in solution:
#"A" + "BC" → "C" + "BA"#
Example: #"Br"_2 + "2KI" → "I"_2+ "2KBr"#

To determine whether a given single replacement will occur, you must use an “Activity Series” table.

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If the metal or the halogen is above the element it will replace based on the activity series, a single displacement reaction will occur.

Examples:

#"Mg" + "2HCl" → "H"_2 + "MgCl"_2# (#"Mg"# is above #"H"#)

#"Cl"_2 + "2NaBr" → "Br"_2 + "2NaCl"# (#"Cl"# is above #"Br"#)

#"Cu" + "AlCl"_3→ "no reaction"# (#"Cu"# is below #"Al"#)

The video below summarizes an experiment conducted to compare the activities of three metals (#"Mg, Cu"# and #"Zn"#).