What is the purpose of adding Zn or Al in a blue Copper (#CuSO_4#) solution?

1 Answer
Nov 8, 2016

Answer:

The purpose is to compare the reactivity of aluminum and zinc to copper. If the aluminum and zinc are more reactive than copper, each will undergo a single replacement reaction with copper sulfate, producing the metal copper as a product.

Explanation:

You are observing whether a single replacement (single displacement) reaction will take place between the elements Zn or Al by adding each to a copper(II) sulfate solution.

The following illustration indicates what happens when a single replacement reaction occurs involving metals.

http://slideplayer.com/slide/1659479/

#"A"# is a metal, #"BX"# is a compound in which #"B"# is a metal cation and #"X"# is an anion, #"AX"# is the new compound containing the cation of the metal #"A"#, and #"B"# is the new metal from the compound #"BX"#. In this reaction #"A"# replaced #"B"# in the #"BX"# compound in the reaction.

We can determine whether a single replacement will take place by comparing the locations of the metals on a metal activity series, or list. A metal on the list can replace any of the metals below it.

The following is a metal activity series.

http://www.ekshiksha.org.in/eContent-Show.do?documentId=93

As you can see, aluminum and zinc are above copper on the activity series, so the aluminum and zinc will replace the copper in the copper sulfate solution.

#"2Al(s)+3CuSO"_4("aq")##rarr##"Al"_2"(SO"_4)_3("aq")+"3Cu(s)"#

#"Zn(s)+CuSO"_4("aq")##rarr##"ZnSO"_4("aq")+"Cu(s)"#