Question

A, B, and C are three elements which undergo chemical reactions according to the following equations.

$$\begin{gathered} A_2{O}_3+2B\to B_2{O}_3+2A \\ 3CS{O}_4+2B\to B_2{\left(S{O}_4\right)}_3+3C \\ 3CO+2A\to A_2{O}_3+3C \end{gathered}$$

1. Which element is the most reactive?
2. Which element is the least reactive?

Answer 1

$$\begin{gathered} 1.A_2{O}_3+2B\to B_2{O}_3+2A \\ 2.3CS{O}_4+2B\to B_2{\left(S{O}_4\right)}_3+3C \\ 3.3CO+2A\to A_2{O}_3+3C \end{gathered}$$

Step 1: Analyse equation 1

$A_2{O}_3+2B\to B_2{O}_3+2A$

• This is the double displacement reaction because two reactants exchange their ions and form new compounds. Here A and B in the reactants get exchanged and form new compounds.
• In this equation, A is replaced by B.
• So compared to A, B is more reactive.

Step 2: Analyse equation 2

$3CS{O}_4+2B\to B_2{\left(S{O}_4\right)}_3+3C$

• This is the double displacement reaction because two reactants exchange their ions and form new compounds. Here B and C in the reactants get exchanged and form new compounds.
• This equation replaces C in the first reactant with B in the second reactant.
• So compared to C, B is more reactive.

Step 3: Analyse equation 3

$3CO+2A\to A_2{O}_3+3C$

• This is the double displacement reaction because two reactants exchange their ions and form new compounds. Here A and C in the reactants get exchanged and form new compounds.
• In this equation, C in the first reactant is replaced by A in the second reactant.
• So compared to C, A is more reactive.

Step 4: Most reactive and Least reactive

• From Equations 1 and 2, it is concluded that B is most reactive than A and C because it is displaced by both A and C.
• Equation 3, shows that A is more reactive than C.
• So C is the least reactive compared to both A and B because it gets displaced by both A and B.

Therefore, B is the most reactive, and C is the least reactive element.