Question

According to the activity series, which of the following single replacement reactions will take place?


LiCl + K yields KCl + Li

Pb(NO3)2 + 2Cu yields 2CuNO3 + Pb

2AlBr3 + 3Mg yields 3MgBr2 + 2Al

CaCl2 + 2Na yields 2NaCl + Ca

Answer 1

Pb(NO3)2 + 2CuNO3 + Pb

Answer 2

Answer: The correct answer is $2AlBr_3+3Mg\rightarrow 3MgBr_2+2Al$ and $CaCl_2+2Na\rightarrow 2NaCl+Ca$

Explanation:

Single displacement reactions are the reactions in which a more reactive element replaces a less reactive element from its chemical reaction.

$A+BC\rightarrow AC+B$

A is more reactive element than reactive B.

The reactivity of metals is judged by the series known as reactivity series. Elements lying above in the series are more reactive than the elements lying below in the series.

For the given chemical reactions:

Reaction 1:  $LiCl+K\rightarrow KCl+Li$

Potassium lies below in the series than lithium. Thus, it will not replace lithium from its chemical reaction. It is not considered as a single displacement reaction.

Reaction 2:  $Pb(NO_3)_2+2Cu\rightarrow 2CuCO_3+Pb$

Copper lies below in the series than lead. Thus, it will not replace lead from its chemical reaction. It is not considered as a single displacement reaction.

Reaction 3:   $2AlBr_3+3Mg\rightarrow 3MgBr_2+2Al$

Magnesium lies above in the series than aluminium. Thus, it will easily replace magnesium from its chemical reaction. It is considered as a single displacement reaction.

Reaction 4:  $CaCl_2+2Na\rightarrow 2NaCl+Ca$

Sodium lies above in the series than calcium. Thus, it will easily replace calcium from its chemical reaction. It is considered as a single displacement reaction.

Hence, the correct answer is $2AlBr_3+3Mg\rightarrow 3MgBr_2+2Al$ and $CaCl_2+2Na\rightarrow 2NaCl+Ca$