Question

which of the follow is a redox reaction?

a.) Ba²⁺ (aq) + SO₄^2- (aq) ----> BaSO₄ (s)

b.) K₂Cr₂O₇ (aq) + 2 KOH (aq) ----> 2 K₂CrO₄ (aq) + H₂O (l)

c.) Na₂CO₃ (s) + 2 HCl (aq) ----> 2 NaCl (aq) + CO₂ (g) + H₂O (l)

d.) 2 Na (g) + Cl₂ (g) ----> 2 NaCl (s)

e.) H₂O (l) ----> H⁺ (aq) + OH^- (aq)

I know the answer is "d" however I do not know why. Can you please explain why "d" is correct and what the other types of reactions are? Thank you very much!

Answer 1

Redox is a reaction where oxidation and reduction both takes place simultaneously. In reaction d

2Na(g) + Cl2(g) --2NaCl (s)

We see oxidation state of both Na and Cl in reactant side is 0 as they both are in their elemantal state and when we go to product side we see sodium Na has oxidation of +1 and chlorine Cl has oxidation state of -1

So there is oxidation of Na and reduction of Cl in a same recatior so this is called a redox reaction.

While other reaction are simply formation reaction (1 , 5 ) 2nd is displacement reaction. Etc