Chemical reaction takes place when iron dust is added into copper sulphate solution but no reaction takes place when copper dust is added into ferrous sulphate solution, why?

2 Answers
Jul 14, 2018

Iron is more reactive than copper


Refer to the reactivity series:

Since Iron is more reactive than copper, that means it has a greater tendency to lose electrons and form positive ion, displacing copper ion in copper sulphate solution.

However, since copper is below iron in the reactivity series, it is less reactive than iron and therefore unable to displace the ferrous ion (#Fe^"2+"#) in ferrous sulphate solution.

Jul 14, 2018

The reaction between copper and ferrous sulfate will not occur because copper is less reactive than iron.


In order for a single replacement (displacement) reaction to occur, the metal in the reactants must be more reactive than the metal in the compound in the reactants. We can use a metal reactivity series to do this. A metal can replace (displace) a metal that occurs below it in the reactivity series.
The first reaction is:

#"Fe(s) + CuSO"_4("aq")"##rarr##"FeSO"_4("aq") + "Cu(s)"#

Since iron is above copper in the reactivity series, it will replace the copper in the copper sulfate compound, so this reaction will occur.

Now let's look at the reverse reaction.

#"Cu(s) + FeSO"_4("aq")"##rarr##"CuSO"_4("aq") + "Fe(s)"#

Since copper is below iron in the reactivity series, it is less reactive than iron, so it will not replace the iron in the compound. So there is no reaction, and the equation should be written as:

#"Cu(s) + FeSO"_4("aq")"##rarr##"no reaction"#