Question

Which of the following redox reactions do you expect to occur spontaneously in the forward direction?

Answer 1

Answer: The correct answer is Option 1 and Option 2.

Explanation:

Redox reactions are termed as the reactions in which reduction and oxidation reactions occur simultaneously.

Reduction reactions are the ones where a substance gains electrons. The oxidation state of the substance gets reduced.

Oxidation reactions are the ones where a substance looses electrons. The oxidation state of the substance is increased.

All the given reactions are a type of single displacement reactions. In this, a more reactive metal displaces a less reactive metal from its chemical reaction. The reactivity is determined from a series known as reactivity series. A metal which lies above in the series is more reactive than the metals which lie below in the series.

$A+BC\rightarrow AC+B$

From the given options:

Option 1: $Ni(s)+Pb^{2+}(aq.)\rightarrow Ni^{2+}(aq.)+Pb(s)$

Here, nickel lies above in the series than lead. Thus, it will easily replace lead from its chemical reaction.

Option 2: $Al(s)+3Ag^+(aq.)\rightarrow Al^{3+}(aq.)+3Ag(s)$

Here, aluminium lies above in the series than silver. Thus, it will easily replace silver from its chemical reaction.

Option 3: $Ni(s)+Zn^{2+}(aq.)\rightarrow Ni^{2+}(aq.)+Zn(s)$

Here, nickel lies below in the series than zinc. Thus, it will not easily replace zinc from its chemical reaction.

Option 4: $Fe^{2+}(aq.)+Cd(s)\rightarrow Fe(s)+Cd^{2+}(aq.)$

Here, cadmium lies below in the series than iron. Thus, it will not easily replace iron from its chemical reaction.

Thus, the correct answer is Option 1 and Option 2.

Answer 2

Among the choices provide above the redox reactions do you expect to occur spontaneously in the forward direction is the below:

Fe2+(aq) + Zn(s) -> Fe(s) + Zn2+(aq) 
 Al(s) + 3Ag+(aq) -> Al3+(aq) + 3Ag(s) 

Those reactions will proceed when the metal that is a solid is higher up in the electromotive series than the metal that is an ion (dissolved).