Q82E - Chemistry (OpenStax)

Question

Write balanced chemical equations for the following reactions:

(a) cadmium burned in air

(b) elemental cadmium added to a solution of hydrochloric acid

(c) cadmium hydroxide added to a solution of acetic acid, \({\rm{C}}{{\rm{H}}_3}{\rm{C}}{{\rm{O}}_2}{\rm{H}}\)

Step-by-Step Solution

Answer

1. The balanced equation of Cadmium cadmium burned in air is \(2{\rm{Cd}}({\rm{s}}) + {{\rm{O}}_2}(\;{\rm{g}}) \to 2{\rm{CdO}}({\rm{s}})\)
2. The balanced equation of elemental cadmium added to a solution of hydrochloric acid is \({\rm{Cd}}({\rm{s}}) + 2{\rm{HCl}}({\rm{aq}}) \to {\rm{CdC}}{{\rm{l}}_2}({\rm{aq}}) + {{\rm{H}}_2}(\;{\rm{g}})\)
3. The balanced equation of cadmium hydroxide added to a solution of acetic acid is \({\rm{Cd}}{({\rm{OH}})_4}({\rm{aq}}) + 2{\rm{C}}{{\rm{H}}_3}{\rm{COOH}}({\rm{aq}}) \to {\left( {{\rm{C}}{{\rm{H}}_3}{\rm{COO}}} \right)_2}{\rm{Cd}}({\rm{aq}}) + 2{{\rm{H}}_2}{\rm{O}}({\rm{l}})\)

Step 1: Defintion of Reaction stoichiometry

• In terms of reaction stoichiometry, a balanced equation depicts the amount of reactants consumed or the amount of products produced.
• Stoichiometry is a mathematical formula that calculates the coefficients of the reactants and products in a chemical process. It denotes the mole ratio at which reactants and products mix to generate products.
• Cadmium (Cd) is a transition metal that has an \({\rm{5}}{{\rm{s}}^{\rm{2}}}{\rm{4}}{{\rm{d}}^{{\rm{10}}}}\) valence electron configuration.

Step 2: Find the balanced equations for cadmium burned in air

Cadmium becomes cadmium oxide when it combines with oxygen. The following is a diagram of the chemical reaction:

 

\({\rm{Cd}}({\rm{s}}) + {{\rm{O}}_2}(\;{\rm{g}}) \to {\rm{CdO}}({\rm{s}})\)

 

The equation is unbalanced because the reactants have two O atoms while the products have only one. Multiply Cd and CdO by 2 to get the following equation to balance it:

 

\(2{\rm{Cd}}({\rm{s}}) + {{\rm{O}}_2}(\;{\rm{g}}) \to 2{\rm{CdO}}({\rm{s}})\)

 

Step 3: Find the balanced equations for elemental cadmium

Cadmium forms cadmium chloride and hydrogen gas when it combines with hydrochloric acid. The following is a diagram of the chemical reaction:

 

\({\rm{Cd}}({\rm{s}}) + {\rm{HCl}}({\rm{aq}}) \to {\rm{CdC}}{{\rm{l}}_2}({\rm{aq}}) + {{\rm{H}}_2}(\;{\rm{g}})\)

 

Because the number of H and Cl atoms on the reactants is 1, while the number on the products is 2, the equation is unbalanced. Multiply HCl by 2 to get the following equation to balance it:

 

\({\rm{Cd}}({\rm{s}}) + 2{\rm{HCl}}({\rm{aq}}) \to {\rm{CdC}}{{\rm{l}}_2}({\rm{aq}}) + {{\rm{H}}_2}(\;{\rm{g}})\)

Step 4: Find the balanced equations for cadmium hydroxide

Cadmium hydroxide reacts with acetic acid to generate cadmium acetate, which is then combined with water to form cadmium acetate. The chemical reaction is depicted in the diagram below.

 

\({\rm{Cd}}{({\rm{OH}})_4}({\rm{aq}}) + {\rm{C}}{{\rm{H}}_3}{\rm{COOH}}({\rm{aq}}) \to {\left( {{\rm{C}}{{\rm{H}}_3}{\rm{COO}}} \right)_2}{\rm{Cd}}({\rm{aq}}) + {{\rm{H}}_2}{\rm{O}}({\rm{l}})\)

 

Because only the number of Cd atoms on both sides is the same, the equation is unbalanced. To balance it, multiply \({\rm{C}}{{\rm{H}}_3}{\rm{COOH}}\)on the reactant side by 2 and \({{\rm{H}}_2}{\rm{O}}\)on the product side by 2.

 

\({\rm{Cd}}{({\rm{OH}})_4}({\rm{aq}}) + 2{\rm{C}}{{\rm{H}}_3}{\rm{COOH}}({\rm{aq}}) \to {\left( {{\rm{C}}{{\rm{H}}_3}{\rm{COO}}} \right)_2}{\rm{Cd}}({\rm{aq}}) + 2{{\rm{H}}_2}{\rm{O}}({\rm{l}})\)