Question

which of the following reactions are double replacement reactions?
o nacl → na + cl₂
o ca + s → cas
o ch₄ + o₂ → h₂o + co₂
o naoh + hcl → hoh + nacl

Explanation:

Step1: Recall double - replacement reaction definition

A double - replacement reaction has the general form \(AB + CD
ightarrow AD+CB\), where the cations and anions of two compounds exchange places.

Step2: Analyze each reaction

• For \(NaCl

ightarrow Na + Cl_2\), this is a decomposition reaction as a single compound breaks down into two or more simpler substances.

• For \(Ca + S

ightarrow CaS\), this is a combination reaction where two substances combine to form one compound.

• For \(CH_4+O_2

ightarrow H_2O + CO_2\), this is a combustion reaction of a hydrocarbon in oxygen.

• For \(NaOH + HCl

ightarrow HOH(=H_2O)+NaCl\), the sodium ion (\(Na^+\)) from \(NaOH\) and the hydrogen ion (\(H^+\)) from \(HCl\) exchange places. This follows the double - replacement reaction pattern.

Answer:

\(NaOH + HCl
ightarrow HOH + NaCl\)