Question

Which reaction will occur?

2NaBr + I2 mc023-1.jpg 2NaI + Br2
2Fe + Al2O3 mc023-2.jpg 2Al + Fe2O3
2AgNO3 + Ni mc023-3.jpg Ni(NO3)2 + 2Ag
Pb + Zn(C2H3O2)2 mc023-4.jpg Zn + Pb(C2H3O2)2

Answer 1

Only the second 2Fe + Al2O3 = 2Al + Fe2O3. In the first reaction iodide can not replace bromide from the salt. In the third reaction lead can not replace more active zinc metal from the salt.

Answer 2

Answer:
`2AgNO3+Ni\rightarrow Ni(NO_3)_2+2Ag`

A single replacement reaction is one in which a more reactive element displaces a less reactive element from its salt solution.

1)
`2NaBr+I_2\rightarrow 2NaI+Br_2`

As iodine is less reactive than bromine, it will not be able to displace bromine from its salt solution, hence no reaction will occur.

2)
`2Fe+Al_2O_3\rightarrow 2Al+Fe_2O_3`

As iron lies lower in reactivity series, it is less reactive than Aluminium. It will not be able to displace aluminium from its salt and hence no reaction occur.

3)
`2AgNO3+Ni\rightarrow Ni(NO_3)_2+2Ag`

As nickel lies above in reactivity series, it is more reactive than silver. It will be able to displace silver from its salt and hence reaction will occur.

4)
`Pb+Zn(C_2H_3O_2)_2\rightarrow Zn+Pb(C_2H_3O_2)_2`

As lead lies lower in reactivity series, it is less reactive than zinc. It will not be able to displace zinc from its salt and hence no reaction occur.