Question

Classify each of the following reactions as a combination, decomposition, single replacement, double replacement, or combustion: a. \(\mathrm{CuO}(s)+2 \mathrm{HCl}(a q) \longrightarrow \mathrm{CuCl}_{2}(a q)+\mathrm{H}_{2} \mathrm{O}(l)\) b. \(2 \mathrm{Al}(s)+3 \mathrm{Br}_{2}(g) \longrightarrow 2 \mathrm{AlBr}_{3}(s)\) c. \(\mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}(a q)+2 \mathrm{NaCl}(a q) \longrightarrow \mathrm{PbCl}_{2}(s)+2 \mathrm{NaNO}_{3}(a q)\) d. \(2 \mathrm{Mg}(s)+\mathrm{O}_{2}(g) \stackrel{\Delta}{\longrightarrow} 2 \mathrm{MgO}(s)\) e. \(2 \mathrm{C}_{2} \mathrm{H}_{2}(g)+5 \mathrm{O}_{2}(g) \stackrel{\Delta}{\longrightarrow} 4 \mathrm{CO}_{2}(g)+2 \mathrm{H}_{2} \mathrm{O}(g)\) f. \(\mathrm{Fe}_{2} \mathrm{O}_{3}(s)+3 \mathrm{C}(s) \longrightarrow 2 \mathrm{Fe}(s)+3 \mathrm{CO}(g)\) g. \(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}(a q) \longrightarrow 2 \mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}(a q)+2 \mathrm{CO}_{2}(g)\) h. \(\mathrm{BaCl}_{2}(a q)+\mathrm{K}_{2} \mathrm{CO}_{3}(a q) \longrightarrow \mathrm{BaCO}_{3}(s)+2 \mathrm{KCl}(a q)\)

Short answer

a. Double replacementb. Combinationc. Double replacementd. Combinatione. Combustionf. Single replacementg. Decompositionh. Double replacement

Step-by-step solution

- Classify Reaction a

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- Classify Reaction b

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- Classify Reaction c

The reaction is . In this reaction,

- Classify Reaction d

The reaction is . In this reaction,

- Classify Reaction e

The reaction is . In this reaction,

- Classify Reaction f

The reaction is . In this reaction,

- Classify Reaction g

The reaction is . In this reaction,

- Classify Reaction h

The reaction is . In this reaction,

Key concepts

Combination Reaction

A combination reaction occurs when two or more reactants combine to form a single product. These reactions can involve elements or compounds. For example, in reaction b: \(2 \mathrm{Al}(s)+3 \mathrm{Br}_{2}(g) \longrightarrow 2 \mathrm{AlBr}_{3}(s)\), aluminum and bromine gas combine to form aluminum bromide.
This process typically involves the formation of a bond between the reactants, resulting in a stable product, which simplifies the reactants into a single substance.

Decomposition Reaction

A decomposition reaction is the opposite of a combination reaction. It involves breaking down a single compound into two or more simpler substances. An example from the exercise is reaction g: \(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}(a q) \longrightarrow 2 \mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}(a q)+2 \mathrm{CO}_{2}(g)\). Here, glucose decomposes into ethanol and carbon dioxide.
These reactions require energy input, often in the form of heat, light, or electricity, to break chemical bonds within the compound.

Single Replacement Reaction

In a single replacement reaction, one element replaces another in a compound. This type of reaction is represented as: \(A + BC \rightarrow AC + B\). For instance, reaction f: \(\mathrm{Fe}_{2} \mathrm{O}_{3}(s)+3 \mathrm{C}(s) \longrightarrow 2 \mathrm{Fe}(s)+3 \mathrm{CO}(g)\). Here, carbon replaces iron in iron(III) oxide.
These reactions typically occur in aqueous solutions and often involve metals or halogens. The reactivity series can predict whether a single replacement reaction will occur.

Double Replacement Reaction

A double replacement reaction involves the exchange of ions between two compounds to form new compounds. It follows the format: \(AB + CD \rightarrow AD + CB\). In reaction c: \(\mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}(a q)+2 \mathrm{NaCl}(a q) \longrightarrow \mathrm{PbCl}_{2}(s)+2 \mathrm{NaNO}_{3}(a q)\), lead nitrate and sodium chloride exchange ions to form lead chloride and sodium nitrate.
These reactions generally occur in aqueous solutions, resulting in the formation of a precipitate, gas, or water.

Combustion Reaction

Combustion reactions are exothermic reactions where a substance combines with oxygen, releasing energy in the form of heat and light. An example is reaction e: \(2 \mathrm{C}_{2} \mathrm{H}_{2}(g)+5 \mathrm{O}_{2}(g) \longrightarrow 4 \mathrm{CO}_{2}(g)+2 \mathrm{H}_{2} \mathrm{O}(g)\). Here, acetylene reacts with oxygen to produce carbon dioxide and water.
Combustion reactions are vital for energy production and typically involve hydrocarbons or organic molecules reacting with oxygen to produce carbon dioxide and water.