Question

give the total ionic equation for the reaction (if any) that occurs when aqueous solutions of lithium sulfide and copper(ii) nitrate are mixed.
○ li⁺(aq) + so₄²⁻(aq) + cu⁺(aq) + no₃⁻(aq) → cus(s) + li⁺(aq) + no₃⁻(aq)
○ 2 li⁺(aq) + s²⁻(aq) + cu⁺(aq) + 2 no₃⁻(aq) → cus(s) + 2 li⁺(aq) + 2 no₃⁻(aq)
○ li⁺(aq) + s²⁻(aq) + cu⁺(aq) + no₃⁻(aq) → cus(s) + lino₃(aq)
○ li⁺(aq) + s⁻(aq) + cu⁺(aq) + no₃⁻(aq) → cus(s) + lino₃(aq)

Explanation:

Step1: Write the chemical formulas

Lithium sulfide is \(Li_2S\) (since lithium has a +1 charge and sulfide has a -2 charge, so we need 2 \(Li^+\) ions to balance the charge of \(S^{2 -}\)), and copper(II) nitrate is \(Cu(NO_3)_2\) (copper has a +2 charge and nitrate \(NO_3^-\) has a -1 charge, so we need 2 \(NO_3^-\) ions).

Step2: Write the molecular equation

\(Li_2S(aq)+Cu(NO_3)_2(aq)\to CuS(s)+2LiNO_3(aq)\) (using the double - displacement reaction rule: \(AB + CD\to AD+CB\), here \(A = Li^+\), \(B=S^{2 -}\), \(C = Cu^{2+}\), \(D = NO_3^-\), and \(CuS\) is insoluble as per solubility rules (most sulfides are insoluble except those of Group 1 and Group 2 metals)).

Step3: Write the total ionic equation

Split the soluble ionic compounds (\(Li_2S\), \(Cu(NO_3)_2\), \(LiNO_3\)) into their ions.
\(2Li^+(aq)+S^{2 -}(aq)+Cu^{2+}(aq)+2NO_3^-(aq)\to CuS(s)+2Li^+(aq)+2NO_3^-(aq)\)

Answer:

\(2Li^+(aq)+S^{2 -}(aq)+Cu^{2+}(aq)+2NO_3^-(aq)\to CuS(s)+2Li^+(aq)+2NO_3^-(aq)\)