# CHEM HELP!!!?

Which of the following is an oxidation-reduction reaction?

A) HCl (aq) + LiOH (aq) = LiCl (aq) + H2O (l)

B) NaI (aq) + AgNO3 (aq) = AgI (s) + NaNO3 (aq)

C) Pb(C2H3O2)2 (aq) + 2NaCl (aq) = PbCl2 (s) + 2NaC2H3O2 (aq)

D) Mg (s) + 2HCl (aq) = MgCl2 (aq) +H2 (g)

E) All of the above are oxidation-reduction reactions.

### 3 Answers

- wanszetoLv 79 months agoBest Answer
A)

HCl (aq) + LiOH (aq) → LiCl (aq) + H₂O (l)

O.N. (oxidation number) of H on the LHS = O.N. of H on the RHS = +1

O.N. of Cl on the LHS = O.N. of Cl on the RHS = -1

O.N. of Li on the LHS = O.N. of Li on the RHS = +1

O.N. of O on the LHS = O.N. of O on the RHS = -2

As oxidation numbers of all elements involved are unchanged in the reaction, the reaction is NOT oxidation-reduction.

B)

NaI(aq) + AgNO₃(aq) → AgI(s) + NaNO₃(aq)

O.N. of Na on the LHS = O.N. of Na on the RHS = +1

O.N. of I on the LHS = O.N. of I on the RHS = -1

O.N. of Ag on the LHS = O.N. of Ag on the RHS = +1

O.N. of N on the LHS = O.N. of N on the RHS = +5

O.N. of O on the LHS = O.N. of ) on the RHS = -2

As oxidation numbers of all elements involved are unchanged in the reaction, the reaction is NOT oxidation-reduction.

C)

Pb(C₂H₃O₂)₂ (aq) + 2NaCl (aq) → PbCl₂(s) + 2NaC₂H₃O₂(aq)

O.N. of Pb on the LHS = O.N. of Pb on the RHS = +2

O.N. of C on the LHS = O.N. of C on the RHS, as both are in C₂H₃O₂⁻

O.N. of H on the LHS = O.N. of H on the RHS, as both are in C₂H₃O₂⁻

O.N. of O on the LHS = O.N. of O on the RHS, as both are in C₂H₃O₂⁻

O.N. of Na on the LHS = O.N. of Na on the RHS = +1

O.N. of Cl on the LHS = O.N. of Cl on the RHS = -1

As oxidation numbers of all elements involved are unchanged in the reaction, the reaction is NOT oxidation-reduction.

D)

Mg (s) + 2HCl(aq) → MgCl₂(aq) + H₂(g)

Mg is oxidized because the O.N. of Mg increases from 0 (in Mg) to +2 (in MgCl₂).

H is reduced because the O.N. of H decreases from +1 (in HCl) to 0 (in H₂).

Hence, it is an oxidation-reduction reaction.

The answer: D) Mg (s) + 2HCl(aq) → MgCl₂(aq) + H₂(g)