Question

A student took cu,fe,zn,al strips separately in 4 test tube labelled as 1,2,3,4.he added 10ml of fresh prepared ferrous sulphate solu. to each test tube as shown below . In which test tube the black residue is obtained and name the product formed

Answer 1

In the last test tube containing Al, the black residue will be formed. The name of the product will be aluminium sulphate. As the displacement reaction takes place.

Answer 2

Answer: Black residue will be obtained in the test tubes having Zinc and Aluminium strips.

Explanation:

Single displacement reaction is defined as the reaction in which more reactive element displaces a less reactive element from its chemical reaction.

The reactivity of metal is determined by a series known as reactivity series. The metals lying above in the series are more reactive than the metals which lie below in the series.

$A+BC\rightarrow AC+B$

Metal A is more reactive than metal B.

When 10 mL of ferrous sulfate solution is taken in the test tubes having Cu, Fe, Zn and Al strips. The reaction in the test tubes follows:

$FeSO_4+Cu\rightarrow \text{No reaction}\\FeSO_4+Fe\rightarrow \text{No reaction}\\FeSO_4+Zn\rightarrow ZnSO_4+Fe\\3FeSO_4+2Al\rightarrow Al_2(SO_4)_3+3Fe$

Iron is getting precipitated in the test tubes having Zinc and Aluminium strips. So, black residue will be obtained in the test tubes having Zinc and Aluminium strips.