Question

which of the following is not a double - replacement reaction?
a hi + ba(oh)2 → bal2 + h2o
b nh4cl + koh → kcl + nh3 + h2o
c zn + cu(ch3coo)2 → zn(ch3coo)2
d ni(no3)2 + naoh → nano3 + ni(oh)

Explanation:

Step1: Recall double - replacement reaction definition

A double - replacement reaction has the general form \(AB + CD
ightarrow AD+CB\), where \(A\) and \(C\) are cations and \(B\) and \(D\) are anions.

Step2: Analyze reaction \(Zn + Cu(CH_{3}COO)_{2}

ightarrow Zn(CH_{3}COO)_{2}+Cu\)
This is a single - replacement reaction. In a single - replacement reaction, an element reacts with a compound and replaces an element in that compound. The general form is \(A + BC
ightarrow AC + B\). Here, \(Zn\) (a metal) replaces \(Cu\) in \(Cu(CH_{3}COO)_{2}\).

Step3: Analyze reaction \(HI + Ba(OH)_{2}

ightarrow Bal_{2}+H_{2}O\)
Rewrite it as \(2HI+Ba(OH)_{2}
ightarrow Bal_{2}+2H_{2}O\). It is a double - replacement reaction (acid - base neutralization, a type of double - replacement). \(H^{+}\) from \(HI\) and \(Ba^{2 +}\) exchange partners with \(OH^{-}\) and \(I^{-}\).

Step4: Analyze reaction \(NH_{4}Cl+KOH

ightarrow KCl + NH_{3}+H_{2}O\)
Rewrite it as \(NH_{4}Cl+KOH
ightarrow KCl+NH_{3}\cdot H_{2}O\) (since \(NH_{3}+H_{2}O = NH_{3}\cdot H_{2}O\)). It is a double - replacement reaction. \(NH_{4}^{+}\) and \(K^{+}\) exchange partners with \(Cl^{-}\) and \(OH^{-}\).

Step5: Analyze reaction \(Ni(NO_{3})_{2}+NaOH

ightarrow NaNO_{3}+Ni(OH)_{2}\)
Rewrite it as \(Ni(NO_{3})_{2}+2NaOH
ightarrow 2NaNO_{3}+Ni(OH)_{2}\downarrow\). It is a double - replacement reaction. \(Ni^{2+}\) and \(Na^{+}\) exchange partners with \(NO_{3}^{-}\) and \(OH^{-}\).

Answer:

C. \(Zn + Cu(CH_{3}COO)_{2}
ightarrow Zn(CH_{3}COO)_{2}+Cu\)